Merge pull request #3747 from capilkey/1.1-accessibility-fixes-3

bigbluebutton-client/locale/en_US/bbbResources.properties

bigbluebutton-client/resources/prod/lib/bbb_blinker.js

.../src/org/bigbluebutton/main/views/ShortcutHelpWindow.mxml

...rg/bigbluebutton/modules/caption/views/CaptionWindow.mxml

.../src/org/bigbluebutton/modules/chat/views/ChatWindow.mxml

...uebutton/modules/present/ui/views/PresentationWindow.mxml

...rc/org/bigbluebutton/modules/users/views/UsersWindow.mxml

.../org/bigbluebutton/modules/videoconf/views/VideoDock.mxml