Fixes #498
 - uploaded plugins now trigger a grunt rebuild - this will invalidate
   current previews
 - changes to the theme will also invalidate previews, allowing grunt
   to rebuild with the new theme
 - fixed issue where an existing adapt_framework dir would kill install
 - removed grunt build from final install screen - can now log in as
   soon as the app is installed without restarting it
issue #498 - updated screenshot routes
fix for failing tests
Merge pull request #500 from adaptlearning/issues/498

Issues/498