CREATED:
- LoginAPI class to handle http responses
- MainActivity class to be opened if login was successful

UPDATED:
 - Changed hardcoded string on the registration page to values in strings.xml
 - LoginActivity class now has async task to handle login on background thread
 - Changed the input type for the username edit text in activity_login to android:inputType="textEmailAddress"
 - Updated the edit text hints in activity_login to use values in strings.xml