title: get ANDROID_BUILD_SDK_VERSION in other gradle file
body: <p>In my Facebook library I has this </p>
  
  <pre><code>android {
  compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
  buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION
  
  defaultConfig {
      minSdkVersion Integer.parseInt(project.ANDROID_BUILD_MIN_SDK_VERSION)
      targetSdkVersion Integer.parseInt(project.ANDROID_BUILD_TARGET_SDK_VERSION)
  }
  </code></pre>
  
  <p>But then I get error it can't find <code>ANDROID_BUILD_SDK_VERSION</code> how can I get the ANDROID_BUILD_SDK_VERSION from the app.gradle file? So that when it is updated there it will also update in the Facebook library?</p>
  
  <p>Thanks for the help in advance </p>