Previous presentation now loads when presenter switches the presentation.
Merge pull request #1 from GaryDeng/fix-chat-button

Fix ChatButton and ParticipantsButton currentState
Merge pull request #21 from SenecaCDOT-BigBlueButton/fixed-previous-presentation-not-loading

Previous presentation now loads when presenter switches the presentation...
Merge branch 'master' of https://github.com/SenecaCDOT-BigBlueButton/bbb-air-client
Merge branch 'master' of https://github.com/GaryDeng/bbb-air-client into fix-chat-button