title: got error when 'npm install' ionic 2 app
body: <p>got error when 'npm install' , please help .
  i got this problem when i try to npm install ionic 2 app,about last year project
  but when i try to build new app using ionic start,got no problem
  please guide me how to solve this because im new to ionic.</p>
  
  <pre><code>&gt; node-sass@3.10.1 install E:\ionic\Section Code (Finished)\node_modules\node-sass
  &gt; node scripts/install.js
  Start downloading binary at https://github.com/sass/node-sass/releases/download/v3.10.1/win32-x64-57_binding.node
  Cannot download "https://github.com/sass/node-sass/releases/download/v3.10.1/win32-x64-57_binding.node": ode:
  HTTP error 404 Not Found
  Hint: If github.com is not accessible in your location
        try setting a proxy via HTTP_PROXY, e.g.
        export HTTP_PROXY=http://example.com:1234
  or configure npm proxy via
        npm config set proxy http://example.com:8080
  &gt; node-sass@3.10.1 postinstall E:\ionic\Section Code (Finished)\node_modules\node-sass
  &gt; node scripts/build.js
  Building: C:\Program Files\nodejs\node.exe E:\ionic\Section Code (Finished)\node_modules\node-gyp\bin\node-gyp.js rebuild --verbose --libsass_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=
  gyp info it worked if it ends with ok
  gyp verb cli [ 'C:\\Program Files\\nodejs\\node.exe',
  gyp verb cli   'E:\\ionic\\Section Code (Finished)\\node_modules\\node-gyp\\bin\\node-gyp.js',
  gyp verb cli   'rebuild',
  gyp verb cli   '--verbose',
  gyp verb cli   '--libsass_ext=',
  gyp verb cli   '--libsass_cflags=',
  gyp verb cli   '--libsass_ldflags=',
  gyp verb cli   '--libsass_library=' ]
  gyp info using node-gyp@3.6.2
  gyp info using node@8.11.1 | win32 | x64
  gyp verb command rebuild []
  gyp verb command clean []
  gyp verb clean removing "build" directory
  gyp verb command configure []
  gyp verb check python checking for Python executable "python2" in the PATH
  gyp verb `which` failed Error: not found: python2
  gyp verb `which` failed     at getNotFoundError (E:\ionic\Section Code (Finished)\node_modules\which\which.js:13:12)
  gyp verb `which` failed     at F (E:\ionic\Section Code (Finished)\node_modules\which\which.js:68:19)
  gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21)
  gyp verb `which` failed  python { Error: not found: python
  gyp verb `which` failed     at getNotFoundError (E:\ionic\Section Code (Finished)\node_modules\which\which.js:13:12)
  gyp verb `which` failed     at F (E:\ionic\Section Code (Finished)\node_modules\which\which.js:68:19)
  gyp verb `which` failed     at E (E:\ionic\Section Code (Finished)\node_modules\which\which.js:80:29)
  gyp verb `which` failed     at E:\ionic\Section Code (Finished)\node_modules\which\which.js:89:16
  gyp verb `which` failed     at E:\ionic\Section Code (Finished)\node_modules\isexe\index.js:42:5
  gyp verb `which` failed     at E:\ionic\Section Code (Finished)\node_modules\isexe\windows.js:36:5
  gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21)
  gyp verb `which` failed   stack: 'Error: not found: python\n    at getNotFoundError (E:\\ionic\\Section Code (Finished)\\node_modules\\which\\which.js:13:12)\n    at F (E:\\ionic\\Section Code (Finished)\\node_modules\\which\\which.js:68:19)\n    at E (E:\\ionic\\Section Code (Finished)\\node_modules\\which\\which.js:80:29)\n    at E:\\ionic\\Section Code (Finished)\\node_modules\\which\\which.js:89:16\n    at E:\\ionic\\Section Code (Finished)\\node_modules\\isexe\\index.js:42:5\n    at E:\\ionic\\Section Code (Finished)\\node_modules\\isexe\\windows.js:36:5\n    at FSReqWrap.oncomplete (fs.js:152:21)',
  gyp verb `which` failed   code: 'ENOENT' }
  gyp verb could not find "python". checking python launcher
  gyp verb could not find "python". guessing location
  gyp verb ensuring that file exists: C:\Python27\python.exe
  gyp ERR! configure error
  gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
  gyp ERR! stack     at PythonFinder.failNoPython (E:\ionic\Section Code (Finished)\node_modules\node-gyp\lib\configure.js:483:19)
  gyp ERR! stack     at PythonFinder.&lt;anonymous&gt; (E:\ionic\Section Code (Finished)\node_modules\node-gyp\lib\configure.js:508:16)
  gyp ERR! stack     at E:\ionic\Section Code (Finished)\node_modules\graceful-fs\polyfills.js:284:29
  gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:152:21)
  gyp ERR! System Windows_NT 10.0.16299
  gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "E:\\ionic\\Section Code (Finished)\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--libsass_library="
  gyp ERR! cwd E:\ionic\Section Code (Finished)\node_modules\node-sass
  gyp ERR! node -v v8.11.1
  gyp ERR! node-gyp -v v3.6.2
  gyp ERR! not ok
  Build failed
  npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.1.3 (node_modules\fsevents):
  npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.1.3: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})
  npm ERR! code ELIFECYCLE
  npm ERR! errno 1
  npm ERR! node-sass@3.10.1 postinstall: `node scripts/build.js`
  npm ERR! Exit status 1
  npm ERR!
  npm ERR! Failed at the node-sass@3.10.1 postinstall script.
  npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
  npm ERR! A complete log of this run can be found in:
  npm ERR!     C:\Users\hafez\AppData\Roaming\npm-cache\_logs\2018-04-10T00_09_01_869Z-debug.log
  </code></pre>
  
  <p>This are my node version</p>
  
  <p>v8.11.1</p>
  
  <p>npm version</p>
  
  <p>v8.11.1</p>