title: Unable to run flutter demo app gives error
body: <p>Error running Gradle:
  Unable to download needed Android SDK components, as the following licenses have not been accepted:
  Android SDK Platform 27, Android SDK Build-Tools 26.0.2</p>
  
  <p>To resolve this, please run the following command in a Terminal:
  flutter doctor --android-licenses.</p>
  
  <p>On checking with Flutter doctor it gives the error:-</p>
  
  <p>flutter doctor --android-licensesAndroid sdkmanager tool not found (/usr/lib/android-sdk/tools/bin/sdkmanager).
  Try re-installing or updating your Android SDK,
  visit <a href="https://flutter.io/setup/#android-setup" rel="nofollow noreferrer">https://flutter.io/setup/#android-setup</a> for detailed instructions. </p>