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 Sounds good to me then. It's not a syntax I'm familiar with, but if it works it works.

I couldn't confirm that though because the error I'm getting is the same one here: https://travis-ci.org/NYULibraries/ichabod/jobs/29733609#L291

It's failing because of a missing support file. I don't see that file in the branch, did you commit it?