Set editor activity title for talkback

The toolbar will display the correct title for visual purposes
while setting the activity title will have talkback read out
the title when entering the activity.

Test: Manually entered editor activity for
  * editing an existing contact
  * adding a new contact
  * viewing a read-only contact
and verified talkback read the proper title.

Change-Id: I77e366073e725734aa8ac29f52bb760b5e58c02f