[FIX] mail: various ui improvements/fixes

* chat windows:
  - input was kicked out of the window on chrome 43
  - don't animate if folded by default (e.g. after a refresh)
  - width and height 100% like in the frontend
  - z-index to make sure that they are over bootstrap active btn,
    but below notifications, and modals

* chatter:
  - internal note: send button renammed to 'Log'
  - send button is the first button again
  - remove annoying form view widget's tooltip

* client action: focus on composer on channel change