Added activateParticipant and addInvitedParticipant to Conversation
Implemented addInvitedParticipant in Conversation
Implemented activateParticipant in Conversation
Implemented findInvitedParticipant in Conversation
Updated ConcreteChatService inviteUser method to utilize invite methods
Updated InviteController to have an acceptInvite method

ACE-96
Formatted code

ACE-96
Removed blank line
Merge pull request #55 from ualerts-org/createInviteAcceptanceController_ACE-96

Added activateParticipant and addInvitedParticipant to Conversation