Created InviteMessage class
ACE-93
Added inviteUser to ChatService and ConcreteChatService
Updated Participant to have a status of "INVITED"
ACE-93
Corrected invite message "to" path

ACE-93
Made message TYPE static
Exception throwing for non-existent users in ConcreteChatService

ACE-93
Updated javadoc on ChatService

ACE-93
Merge pull request #52 from ualerts-org/createInviteMessage_ACE-93

Create invite message ace 93
Added constructor to UserIdentifier to take single string (user@domain)
Updated UserIdentifier tests to test the new constructor

ACE-92
Created base InviteController. May need revision with progress

ACE-92
Actually added comments ACE-92
Added Exception catching for non-existent users
Fixed typo
Merge branch 'createSpringPostControllerToHandleInvite_ACE-92' of
https://github.com/ualerts-org/ualerts-chat into
createSpringPostControllerToHandleInvite_ACE-92

Conflicts:
	org.ualerts.chat.web/src/main/java/org/ualerts/chat/web/controller/InviteController.java