Use menu_block in more places.

Also a small refactoring of menu_block internals.
Removed the old, now unused nav helper.
Fixing stray "=" that snuck in.
It's Monday. I screwed up twice.

Putting the permissions checks I missed back in.
Merge pull request #95 from biola/more_menu_block

Use menu_block in more places.
Hide biola affiliation if none exists.
This was throwing an error when creating a new person because affiliations was `nil`.
Merge branch 'master' into making_bio_its_own_controller