Show media_entry when it has a custom url #master-hot-fixes #FIX

Conflicts:
	config/deploy/stable_version.rb
Reset session when corresponding user is not found #master-hot-fixes #FIX

Try to avoid endless loop
robots.txt: disallow indexing of styleguide
Remove render call (hack on top of hack, ...) #FIX

This is a patch on top of a larger problem. It redirects
to the login page when a set is requested without permissions.
clean up meta terms after db refactoring
Update stored schema
assets: move default zhdk logo from /app/assets to /public as per current version of sprockets

This was a change in Rails 4, see <https://github.com/rails/sprockets-rails/blob/94a033289ba895c036b73527ca5e567d88a35e58/README.md#changes-from-rails-3x>
> "Only compiles digest filenames. Static non-digest assets should simply live in public/."
[admin] show metakey contexts; ability to filter list