AJAX in Post Editor + Keyboard Shortcut for Saving

In addition, here I also show the progress indicator in the title bar because I don't want to edit the CSS layout just to make the notification message sticked to the top of screen (whenever you scroll the page). 

Considering now the users can save or update the post by pressing key combination **CTRL + S**, so they no longer need to scroll the window up just to see what happens with dat **Save** and **Update** button plus the notification messages. At least now we can see the saving progress through the title bar without having to scroll the screen up! 

Maybe not realy important for version 0.9, but if you want to implement my idea to the future versions...
Merge pull request #561 from tovic/patch-12

AJAX in Post Editor + Keyboard Shortcut for Saving