Add chat to "manage" agenda item

Incorporate chat in the -app/agenda "manage" section for Speaker ease of use opportunity.

Current : Poll results that are hidden from attendees show on a different page from chat. Moderators and speakers currently need to access the agenda items main page to view and respond to chat. Then click manage to view poll responses. To see all possible chat questions from attendees, speakers and moderators and speakers have to toggle between two pages. 

Idea : All communications to/ from attendees and admins/speaker/moderators are on one page separated by tabs