Ability to manage profile photos
Ability to set a ProfilePhoto as primary.

Which sets Person#profile_photo_id and Person#profile_photo.
WCMS-200
Make biola_person_image pull from profile_photo.

If a person has one.
Fix bugs in ProfilePhotoController.

Fix error when unchecking "primary" checkbox.
Unset Person#profile_photo_id if ProfilePhoto is deleted.
Flash message when ProfilePhoto can't be created.
Merge pull request #66 from biola/profile_photos

Ability to manage profile photos