also link to dataset from level icon
added flag to remove datasets from view
removed datasets don't appear on public index
allow users to be admin
admin update actions
interface to allow admins to remove datasets
added readme section
Merge remote-tracking branch 'origin' into admin-functions

Conflicts:
	db/schema.rb
Fixed issue where URLs validation doesn't update
Fixed survey sidebar misalignment
Updated error messages for new URL error
Updated URL field to show an explanation field if invalid
Removed unused code
Added a couple of utility plugins
Cleaned up surveyor code
Heavily refactored frontend JS
Added ability to check if a question is required for all levels
Fixed bug which broke question updates
added juvia_rails plugin
started note about environment variables