Create activity entry timeline (OStatus)

[Tryggvi Björgvinsson]

Look into and check if models in GMG are in line with OStatus
objects and activity entries. Create necessary models.

This will probably need discussion on what to include in the first
around and what to exclude. First round should at least contain
Image and Comment objects, as well as the post verb.

Add signal functions or something similar to create entries when a
user posts a new Image or a Comment or access activity information
by some other means (depends on the implementation). Keep in mind
that GMG must be able to support other verbs (e.g. favorite,
follow) so reading directly from MediaEntry model is probably not
the optimal solution.

[Will Kahn-Greene]

The original url for this bug was ​http://bugs.foocorp.net/issues/657 .

[Matt Molyneaux]

Closing as we're now using the Pump API.