Added Homepage

[wiltonmiller]

This pull request is about adding a Homepage to the PingChatz app, the following updates have been made the files added:

• HomePageView: A view for the home page that contains the name of the homepage along with various other objects such as a Signup Button, Login button, and a paint component method that attempts to set the background to an aesthetically pleasing gradient.
• Signup and Login Use Cases Updated: Minor methods have been added to update the SignUp and Login use cases. Both now have the method swtichToHomePageView which is done upon clicking both of their cancel buttons in their View classes.
• App Builder Modified 1: The app builder class has been modified to contain a addHomePageView method which adds the homepage to the layout, the default View upon starting the app has also been set to the HomePage.
• App Builder Modified 2: In addition to this method two instance variables of SignppContoller and LoginController have been added, as they are need for the HomePageView class to be able to switch to the Login and SignUp views when each button is pressed.

[Benjamin-Gavriely]

Amazing looking home page