remove sdkVersions from Example manifest per #63

Example/android/app/src/main/AndroidManifest.xml

     <uses-permission android:name="android.permission.READ_CONTACTS"/>
     <uses-permission android:name="android.permission.READ_CALENDAR"/>
 
-    <uses-sdk
-        android:minSdkVersion="18"
-        android:targetSdkVersion="23" />
 
     <application
       android:name=".MainApplication"