Wrapping user permissions up into the user model so that they can be shared in different places. Specifically which affiliations a given user is allowed to see.
filter facets by user permissions

Even if a user can search for a certain person in the directory, they
shouldn’t be able to see the affiliation facets that don’t have access
to see. This will filter out the facets they are not permitted to see.
Break user affiliation permissions out

This will be a little easier to reuse. The problem was that we kept
having to check if user was nil and return `[:faculty, :trustee]` if it
was. This takes care of that.
Limit tags to affiliations user can see

On the people show page, only list the affiliations that the user is
allowed to see. In the future we will need to filter down the
information on the page as well.
Merge pull request #16 from biola/DIR-61_fix_facet_visibility

Dir 61 fix facet visibility