Make some properties single valued. Fixes #706
Handle the more restrictive singular/multiple fields

Conflicts:
	app/views/records/edit_fields/_default.html.erb
	app/views/records/edit_fields/_description.html.erb
	app/views/records/edit_fields/_rights.html.erb
	spec/views/catalog/index.html.erb_spec.rb
	sufia-models/app/models/concerns/sufia/generic_file/web_form.rb
Adjust string/arrayness of properties
Set multiple to false for on_behalf_of and proxy_depositor
Update to hydra-jetty 8.1.1
Using new versions interface

ActiveFedora::Versionable now uses objects to represent each version of
a resource.
Bump to active-fedora beta 6
Run audits on ResourceVersion instead of uris

This brings Sufia’s audit process inline with ActiveFedora’s
updated version interface.
Check for uniqueness of the field by using the existing class method
Remove unused css_head and js_head yields
Merge pull request #760 from projecthydra/remove_head_yields

Remove unused css_head and js_head yields
Merge pull request #758 from projecthydra/beta-6

Beta 6