Monitor all request, sync, and error events in application

Respond with a spinner graphic
Update source styling and use source template in multiple places

Also update some styles
Update navbar style
Add button to delete database

Temporary while futzing a lot
Adapt period editing view to recent changes

Most importantly, monitor changes to nested period.start and period.end
models.
Add update function to the Backbone-Dexie connector
Move backbone-relational Dexie addon to its own module
Reorganize internal organization of Dexie addon

Attach functions to the appropriate objects/prototype chains, mostly.
This will make things easier to test.