Added Username and Password inputs
Added Login and Register buttons to Login Activity
Added icons to login action bar
Added an explanation TextView to login

This TextView gives a small explanation to the user about what
Hushush is. It's short and sweet.
Added in user login validation to LoginActivity

When the user attempts to log in, the app now checks if the username
and password lines are empty. If either are, a Toast is displayed
telling the user to fill in whatever line is empty.
Merge branch 'login' into develop
Created simple Sign Up activity

Allows the user to sign up for a new account. No actual functionality
yet.
Changed logic for logging in

When you are not logged in, LoginActivity is displayed when you
first open the app. If you are logged in, however, ConversationsActivity
is displayed instead. Nifty!
You can now logout from the ConversationsActivity

When you logout, a setting is toggled that puts you back to the
LoginActivity.
Merge branch 'signup' into develop
Up navigation enabled on SignUpActivity

Instead of fiddle-fucking with the back stack, Android "Up" navigation
has been enabled on the SignUpActivity, to bring you back to the
LoginActivity.
Implemented a dialog for logging out

When you choose to log out of the app, a confirmation alert dialog
appears.
Merge branch 'signup' into develop
Merge branch 'develop'