Improve storage/functionality of glossary terms

Store glossary terms and definitions http://qmh.haverford.edu/glossary/ in Django database (talk to @mzarafon  before doing this), rather than manually updating html page (as is the case now). For everywhere the terms are referenced on the site (already tagged as class="glossary"), have definitions appear as hover text/tool tip. The definitions should be pulled from the database.
