Remove the old rule sets and routing logic

We no longer need to support /folder /module etc. So remove the flask-route
setup and also remove the logic those URLs would point to.
change logic of obj_from_urn

originally we decided which object model to use based on the URI/URL
This is no longer possible (arguably not good practise either).  So
we now look for the SQLAlchemy model in each table that has the given
UID.  If we find it, we return the object.  We cannot know in advance
which model the UUID applies to (ie GET folder or GET collection) so
we try all three.  SqlAlchemy fights my attempts to search then retrieve.
Add lookup from a mediaType to model class
Add lookup from a mediaType to model class
Fix generic routing to call correct models.

We needed to add a few lines to ensure we looked up the correct model for
uid and then called the generic_x
Tests changed to reflect above