Pixel perfect: Message view

Still waiting for a few missing assets, but it's done other than that.

The divider change is already merged; new layouts all use the framework style.

It's basically all layout changes, except for:
- Now the recepient address line has "Show details", which shows a dialog with
  all to/cc/bcc addresses with the timestamp.
- Now invite response buttons are checkboxes.
  (But the basic behavior doesn't change -- once you check a response,
  the message will be gone, so you can't change the response later.)

Copied message_header_bg from gmail manuall.  It'll look silly without it.

Bug 3138021
Bug 3307021

Change-Id: I6f7eb91d6104c3143a5c58b0c4c6c19929cea477
3 files changed