Add Person#groupings field

This will be used to store the "schools" from the faculty.biola.edu
API and other tag-like data in the future.
Remove blank entries from Person arrays.

We may want to do something similar on other models that have Array
fields but for now I'm going to keep it simple and try it out here.
Merge pull request #112 from biola/groupings

Add Person#groupings field
Version bump to v0.39.0
Auto setting the bio slug to person slug if there is one, on bio create and person update.
removed binding.pry
fixed bug
Clean out the database before FactoryGirl.lint

To prevent errors from left over database data.
added specs and made suggested changes
Merge pull request #113 from biola/bio_slug

Auto setting the bio slug to person slug if there is one, on bio create and person update
Merge pull request #114 from biola/fix_db_data_errors

Clean out the database before FactoryGirl.lint
Version bump to v0.40.0
Merge branch 'master' into adding_tags