Add API modules to Flow.

For now, just the one Query module, which will bring up the blocks
that comprise a workflow (given the workflow page name and possibly
its ID) in a machine readable format. Still definitely needs paging
and so on.

Includes a write API as well, and a bare bones base JS module
with access to the API actions. Eventually the JS module will have
shortcuts to the most common actions (post, reply, etc).

Change-Id: I3115567c29af31c6754e297f1f3fc3485edb9deb
Merge "Add API modules to Flow."