Bug 838011 - Implement saving email to a contact

https://bugzilla.mozilla.org/show_bug.cgi?id=838011

Major changes made as the following:
- Email
  * Added "create new contact" and "save to existing contact" menu items
  * Added logics for creating corresponding web activities.

- Contact
 * Added a new web activity called "edit" enabling users to pick a contact and edit.
 * Added a case in the 'dataPickHandler" function for editing contacts. 
 * Added unit tests for testing the "activity" object.