title: About productFlavors with gradle
body: <p>I have some problem with <code>productFlavors</code>. For example in <code>AndroidManifest.xml</code>:</p>
  
  <pre><code>&lt;meta-data android:name="UMENG_APPKEY" android:value="51a5692756240bfa33032a55" /&gt;
  &lt;meta-data android:name="UMENG_CHANNEL" android:value="Authority" /&gt;
  </code></pre>
  
  <p>I want to change the <code>Authority</code> value through <code>productFlavors</code>, anyone can help me?<br>
  I try to set like this but it doesn't work.</p>
  
  <pre><code>    productFlavors {
      playstore {
          packageName='com.android.newsp.playstore'
          versionCode 15
          UMENG_CHANNEL="Authority"
      }
      hiapk {
          packageName='com.android.newsp.hiapk'
          versionCode 100
          UMENG_CHANNEL="ChannelA"
      }
  }
  </code></pre>
  
  <p>I try it, I found the mainfests don't merged as I hope. I copy two <code>AndroidManifest.xml</code> and change the <code>UMENG_CHANNEL</code> value. Then I put them in the folder:</p>
  
  <pre><code>    productFlavors {
      playstore {
          packageName='com.android.newsp.playstore'
          versionCode 15
      }
      hiapk {
          packageName='com.android.newsp.hiapk'
          versionCode 100
      }
  }
  
  sourceSets {
      hiapk {
          manifest.srcFile 'hiapk/AndroidManifest.xml'
      }
      playstore {
          manifest.srcFile 'playstore/AndroidManifest.xml'
      }
      instrumentTest.setRoot('tests')
  }
  </code></pre>