Added RosterAddedController
Refactored Controller API to include getRosterAddedMessage and
getRosterRemovedMessage methods. Refactored UserName to check for null
prior to checking for isEmpty. Refactored ConcreteConversation for
structure.
ChatController performs a POST to the service on name being submitted

ACE-45
Correct ChatService line 89 submitName method

ACE-44
Refactored UserName to handle NULL case and fixed associated errors
Added check on UserName constructor to throw an IllegalArgumentException
if the userName argument is null or empty
Removed call to getRosterRemovedMessage from removeParticipant method
Added set name with UUID in default constructor of UserName
Added @Autowired annotation to the setChatClientContext method
UI view of participants

ACE-41
Removed the participantsMap from Conversation and ConcreteConversation.
Replaced references to NullUserName with the NULL_USER reference in
ConcreteConversation, NameCheckController, RosterAddedController, and
SockJsHandler.
Refactored ConcreteConversationTest due to removing participantsMap and
refactoring isValidUserName in ConcreteConversation.
Refactored RosterAddedController to return 'invalid' if the Participant
is a NULL_USER.
Bug fix: disable name button on load, and enable when the name is valid

ACE-42
Bug fix: Modify validating condition for fast typing.

ACE-42
Removed the getRosterAddedMessage method out of the Conversation
interface and moved it to the RosterAddedController class
Handle type ROSTER_ADDED: append username to connected-users table

ACE-42
Cleaned up code (imports, formatting, etc.)
Merge pull request #14 from ualerts-org/createRosterAddedController_ACE-44

Create roster added controller ace 44