Direct Beaker integration

[Christopher Allan Webber]

We should bundle Beaker directly into GNU MediaGoblin. Right now
it's set up as middleware in server.ini, but this isn't ideal for
the following reasons:


-  Beaker is in no way optional middleware. It's absolutely
   essential for launching the application.
-  Things like ./bin/gmg shell don't give you a fully functioning
   application because they just read mediagoblin.ini which doesn't
   contain information on how to set up Beaker, so it is never set up
-  We need to have a paste config in order to launch tests
-  Complicates writing scripts that interface with mediagoblin So
   here's a solution.
-  Create a ['beaker'] section in mediagoblin.ini and
   mediagoblin/config\_spec.ini
-  Add a utility to create the beaker instance based on the
   ['beaker'] section of the config
-  Use that utility in MediaGoblinApp.**init**() and push it into
   mg\_globals