Add action buttons to new email notifications

Another new feature from Slim!

Works similar to Gmail in that single messages have action buttons.
Each action can be toggled on/off, allowing you to revert back to stock functionality.

Buttons: Mark read, Reply, Delete

Screenshot: https://dl.dropboxusercontent.com/u/2094658/d2att/email_notification_buttons.png

ps4: Fixed intents

Change-Id: Ifa23298d859dc045d943b386b106a8aee76ec2c6