Feature/edit metadata authorization

I assume that pds_handle contain user group name(s) and thus we don't need to add roles. To reflect this I added customized method "groups" to user model. If the assumption is incorrect I will fix it and edit roles file.

@ekate This line is the reason why Travis is failing on this and why coverage has gone down 25% (https://travis-ci.org/NYULibraries/ichabod/builds/29733608). When I run these tests I can't find this file. Is it possible you didn't push it?

Also, the name should be a little more specific to the purpose of the macro functions inside it. Are they user functions all? Then something like `support/users_macros.rb` or `users_helper.rb` might be better