make app name update in Applications tab upon save

http://manage.dimagi.com/default.asp?59384

Two basic parts:
(1) Clear applications tab cache upon save so when you reload the tab menu recomputes
(2) Have the DOM update upon save

Part (2) was slightly trickier. I ended up tagging the menu item with a `data-id` attribute and then having the code that saves changes the app name recompute the title for that menu item and send it back in the response.