Merge pull request #2 from mrubel92/master

Testing on Desktop
Fixed compilation errors.
Implemented token class
Fixed Eclipse warnings
Testing multiple commit push
Implemented method that asks for valid username
Modified .gitignore
Implemented Groups into GroupServer
Working GroupServer and GroupClient

C.java - Created to store all constants
Client.java - Implemented 'connect' function that connects Clients to Servers
GroupClient.java - Only inserted constants from C.java
GroupServer.java - Only inserted constants from C.java
GroupThread.java - Only inserted constants from C.java
RunClient.java - Used to run GroupClient.java and FileClient.java
RunGroupServer.java - Only inserted constants from C.java
Token.java - Implemented toString
UserToken.java - Extended Serializable

RunClient is where the Group and Server clients implement their methods such as getToken, createUser, download, etc.
added file list functionality