This should hopefully help some with performance, and it paves the way for
moving other slow cross-system integration stuff into offline processes.

This handles (as you can see) both new updates which get their request set to
testing as well as updates that get edited. For updates that get edited, we
only sync up new bugs that have been added. Pre-existing bugs don't get
bothered.

A couple not related changes worth mentioned:

• I moved the bodhi masher into bodhi.consumers.masher, for namespacing.
• When new updates are created, I switched the order of assigning the alias and
  setting the request. Setting the request publishes a fedmsg message, and
  it's helpful to have the alias already assigned at that point (so we can use
  the alias in fedmsg consumers).

This changeset is relevant to tickets #314, #301 and #272.