Implementation in Parse: Connect to Parse in Android

1. Get the App ID and client key in the app's setting --> application key page
2. Download the Parse SDK for Android
   https://www.parse.com/downloads/android/Parse-Starter-Project/latest
   and add it to the Android project
3. In the project code (init part), use the App ID and client key to init the Parse SDK
4. Call Parse SDK to manipulate the cloud data
1. ParseObject
1. getString
2. getBoolean
3. ...
4. put("FIELD_NAME", value)
5. saveInBackground
2. ParseQuery<ParseObject>
1. whereEqualTo("FIELD_NAME", value)
2. findInBackground(new FindCallback<ParseObject>(){...})