Add container for cnxs between Projects & Topics

In ae2763a, we migrated to a more distributed topic model. However, I
made a mistake when I created the migrations 008{7,9}. While the
TopicName, TopicSummary, TopicNodeAssignment models were appropriate,
there should have been a container that grouped all those into one
Project -> TopicNode connection, ala the model being developed by the
W3C's Linked Data Platform. To do so, not only did I have to edit the
models, but I had to update the frozen ORM for every revision we made
since 0087 (I know, I know... My lord do I know...). Let's hope that
this is the end of changing the database around.

Additionally, the biggest data migration (0089) let a lot of stuff fall
through the cracks, chiefly because a lot of our revisions lacked a
user_id field specifying the creator of a version/revision. So before
migrating to the distributed topic stuff, I added a function to fix
those user-less revisions (through inspecting last_updater or creator
values in their versions).

I'm tired.