Add div for validation in view, and ChatController.handleValidity

ACE-7
Add ChatService.checkUsername method

ACE-7
Put handleValidity in ChatController.js

ACE-7
Merge branch 'chatSessionUserName_ACE-7' of https://github.com/ualerts-org/ualerts-chat.git into chatSessionUserName_ACE-7
Added set for participant on chat client in sock js handler