<bugfix>Add ability to migrate tags when upgrades are not delayed</bugfix>
<bugfix>Add ability to migrate tags when upgrades are not delayed</bugfix>

Factored the code to migrate tags and notes out of
flush_delayed_actions so that it can be called from the code that
persists immediate upgrades.

core/vistrail/controller.py:
  - VistrailController.migrate_tags: new method
  - VistrailController.flush_delayed_actions: factor out migrate_tags
  - VistrailController.handle_invalid_pipeline: add call to
    migrate_tags for immediate upgrades

Nikea/VisTrails,hjanime/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,Nikea/VisTrails,celiafish/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,minesense/VisTrails,VisTrails/VisTrails,minesense/VisTrails,hjanime/VisTrails,hjanime/VisTrails,Nikea/VisTrails