App restructure

[mradamcox]

Move the individual apps within the main project, cleaning up the root directory. Also took the opportunity to:

• move some globally useful utils, etc, out of loc_insurancemaps
• move views and urls out of the loc_insurancemaps app and into frontend (these were all general views, like home page)
• create a new snippets app to hold legacy and random management commands (part of a longer cleanup effort)
• had to use @app.task instead of @shared_task for celery, as the latter caused the tasks to not be properly set through their routes
• a few random small bugfixes