Progress indicators

Provide a progress indicator for searches. Searches can be slow (especially if it is a remote search), so users need an indicator of ongoing activity.  

Remove the progress indicator from the message list footer.  More often than not, it wasn't useful because it was scrolled out of view.  Even when the footer is visible, a user could hit the "Load up to 25 more" button and the footer will scroll out of view as the messages are loaded.  Instead, use the "check mail" menu button as a progress indicator.

Generally speaking, if there is a "check mail" menu button visible, then it is used as the progress indicator in the above instances, otherwise an indicator is put in the action bar to the right of the title.