Bump versionCode for 1.7.2 release

Author: kevinsawicki

app/AndroidManifest.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.github.mobile"
-    android:versionCode="1500"
+    android:versionCode="1600"
     android:versionName="1.7.2" >
 
     <!-- Target SDK version must be 16, not 17, or JavaScript bridge for