COMMIT

CREATED:
- None

UPDATED:
- RegistrationDialog:
	changed the try/catch for onPostExecute, it now catches  JSONException,NullPointerException & Exception
	added validateInput() method to check the users input

- LoginActivity:
	changed the try/catch for onPostExecute, it also catches  JSONException,  NullPointerException & Exception
	added the method exceptionError(String errResponse) to display the exceptions in a  dialog