Identicons: Add identicons to ChaOS Lab [2/3]

When enabled, new contacts will be assigned a unique
5x5 identicon as the contact photo instead of the boring
default one.

PS2:
Modify the selection used when updating a contact photo.
This seems to reduce the number of unchanged contacts after
the service is done running.

PS3:
Use the new GithubIdenticon class for now.

PS4:
Fix the creation service so it now correctly updates contacts
without photos by assigning an identicon.  Also added a removal
service which will go through and look for photos that have
been tagged as an identicon and remove it.

PS5:
Switch to JPG format and batch removal of identicons.

PS6:
Add identicons styles

PS7:
Add dot matrix style

PS8:
Clean up for release and add proper ChaOS Lab annotations.

Change-Id: Ie7f7a287b3b69d1eb498acd89c62b3b34ed7a875