use proper http accept record
Improve OWL API request header check

Now, we use accept header ordering computed by
rails. As long as the q-values don't change, in
their ordering, we have more robust code now.

This code is about to be deleted/reverted together with
0a4106958a2950ecde156cacae0e9702dc819867.
Merge branch 'hotfix-check_proper_request' into develop

Conflicts:
	app/controllers/files_controller.rb