Allowing member to set status of image membership

Only the owner of an image can add members to the image.
By default the status of the image member is requested.
The member can change the status of the image membership
to accepted or rejected. This is done to prevent spamming
the user's image list. A member cannot see the other members
of the image.

Related to bp glance-api-v2-image-sharing

Change-Id: I0d0deba4b0df52b2f8d105b779fb7de746229d3a
Updates OpenStack LLC with OpenStack Foundation

Patchset addresses reviewer's comments, rebase against master,
and follows new guidance from Foundation:
http://wiki.openstack.org/Documentation/Copyright

Change-Id: I94367461505778973528eb8835d991f4fb796dab
Merge "Updates OpenStack LLC with OpenStack Foundation"
Merge "Allowing member to set status of image membership"