Javadoc descriptions for classes and methods to multiplayer classes

[brjohnson61]

Add javadoc annotations to the new multiplayer classes (MainMenu, Matchmaking, JoinServer, HostServer) and their methods to make the code more descriptive and easy to understand. This will allow the following quarter's students to read through the code on the online javadoc, instead of reading every single line of code and trying to find where it redirects. This will make it less confusing at the start of the project and therefore is a very important aspect of this project. Also this process will familiarize you with the different types of tags and javadoc formatting options.

[YunSuk]

F17 OK.
50 points

[brianslee]

W18 Ok 50 Points