Refactor methods/events for user leaving iteractions

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

...button-html5/imports/api/users/server/methods/kickUser.js

...ports/api/users/server/methods/listenOnlyRequestToggle.js

...ton-html5/imports/api/users/server/methods/userLeaving.js

...tton-html5/imports/api/users/server/methods/userLogout.js

.../imports/api/users/server/modifiers/requestUserLeaving.js

...imports/api/users/server/modifiers/setConnectionStatus.js

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

bigbluebutton-html5/server/main.js