show/hide userslist #459

Added an icon in the index.html.tmpl underneath app_tools. I decided to add it there so that the entire right_bar can be hidden and then unhidden easily. 
I added the event handler for the icon in apptoolbar.js. I decided to use .toggle() because toggleClass() was removing the styles for right_bar, but keeping the styles for memberlists and toolbar. The toggle method simply sets the div's css display to none, so this seemed like the best choice.