Fixed active widget on page load

- The active widget, if one exists in the location hash, will now be
properly activated
- On page load if no existing hash exists, the page will check for
recently imported sections/controls, activating the appropriate widget
as necessary
Mapping from the LHN now activates the appropriate widget
Make post-import redirects point to affected widgets

* Should be more reliable than inferring post-import state from flash
  messages
* Also avoids #null hash on import pages
Merge pull request #361 from reciprocity/feature/activate_widget

Fixed widget activation on page load (via existing hash or recent import)