Improve Contacts' permission handling

Instead of repeatedly asking the user for the same permissions
over-and-over, instead only ask them once when they open an activity.
If they give us all the permissions we require, then allow them to continue.
If not, close the activity and show the user a toast.

Bug: 21791169
Change-Id: Idae927d525124ed8a7081bd5a8edbd24e1ba3190