Tabbed UI (by @enlore)

A refactored frontend that makes a lot more sense than before. The new tabbed UI doesn't duplicate as much information, and immediately displays charts to the user. It also uses bright lines to display change in demographics over time, a huge improvement over the sloppy line charts before.

v2.2.2: Remove import of tables.py from data load

This fixes Issue #62.  tables.py was being imported before the tables were populated by table_check, resulting in top level table references being defined as None and throwing errors further downstream. This included the bad API call to /api/departments.