Code Refactoring For  Credential Manager and Login Classes

@bdonald25 Don't pull this unless you are ready to patch up all the applications.
Also, see me when you get a chance so I point out some things in your code.

@balabhv Take a look at how I've organized the Login Class for future reference.

Getting a username and password is now as easy as:
 - Login.getUsername(Context);
 - Login.getPassword(Context);
 - Login.setCredentials(Context, String username, String password);