Merge pull request #5929 from jfsiebel/add-html5-group-chat-support

bigbluebutton-html5/imports/api/chat/index.js

bigbluebutton-html5/imports/api/chat/server/eventHandlers.js

...ton-html5/imports/api/chat/server/handlers/chatHistory.js

...ton-html5/imports/api/chat/server/handlers/chatMessage.js

...mports/api/chat/server/handlers/chatPublicHistoryClear.js

bigbluebutton-html5/imports/api/chat/server/index.js

bigbluebutton-html5/imports/api/chat/server/methods.js

...ebutton-html5/imports/api/chat/server/methods/sendChat.js

...button-html5/imports/api/chat/server/modifiers/addChat.js

...ton-html5/imports/api/chat/server/modifiers/clearChats.js

...orts/api/chat/server/modifiers/clearUserSystemMessages.js

bigbluebutton-html5/imports/api/chat/server/publishers.js

bigbluebutton-html5/imports/api/group-chat-msg/index.js

...-html5/imports/api/group-chat-msg/server/eventHandlers.js

...pi/group-chat-msg/server/handlers/clearPublicGroupChat.js

...button-html5/imports/api/group-chat-msg/server/methods.js

...i/group-chat-msg/server/methods/clearPublicChatHistory.js

...rts/api/group-chat-msg/server/methods/sendGroupChatMsg.js

...ts/api/group-chat-msg/server/modifiers/addGroupChatMsg.js

.../api/group-chat-msg/server/modifiers/clearGroupChatMsg.js