Implemented functionality of lock settings

...5/imports/api/meetings/server/handlers/meetingCreation.js

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

...imports/api/meetings/server/methods/toggleLockSettings.js

.../meetings/server/methods/toggleWebcamsOnlyForModerator.js

...html5/imports/api/meetings/server/modifiers/addMeeting.js

...on-html5/imports/ui/components/lock-viewers/component.jsx

...on-html5/imports/ui/components/lock-viewers/container.jsx

...tton-html5/imports/ui/components/lock-viewers/styles.scss

bigbluebutton-html5/private/config/settings.yml