[address book] Impossible to delete a photo of a contact

[taiebot65]

It is currently impossible to delete an inserted picture from a contact, you can only change it by selecting another picture but not go back to the default icon with the initial of the contact.

------- UX comment & resolution --------

Once a contact has a picture in the avatar, "Edit" should appear below the avatar icon.
To remove the image:
1. tap the avatar icon
2. a popover appears asking to Change or Remove the picture
3. tap Remove to delete the picture
4. tap Change to bring up the content hub and select a source to set a new picture

For the latest visual design refer to the telephony visual spec:
https://docs.google.com/presentation/d/1XMHRg7T3KxMizExeRTmXJGar0WOUyBQ4A8lEMnQvcqA/edit#slide=id.g18adf9eae_59

For latest UX please refer to this spec:
https://docs.google.com/document/d/1BRy9-DEXr3A1D7PHkJaXmjbe7xbRmxKkzANXuu-F6lc/edit

Visual design is attached to this bug.

[Torsten Franz (torsten.franz)]

I think that the same issue is also reported here: https://bugs.launchpad.net/ubuntu/+source/address-book-app/+bug/1438254

[Olga Kemmet (olga-kemmet)]

Bug description updated and solution attached, marking as Fix Committed.