Consolidate @javascript tags
Move Transition::Hits::Category to models/view

This lets us reload more easily than lib will
Add a View::Hits::TimePeriod object

Helps with rendering the view, and also allows us to look up
a pre-cooked time period by slug.
Allow selection of TimePeriod for hits
Make no_content_message right for time periods
Remove unused Cucumber steps
Let TimePeriod cope with arbitrary ranges
Correct summary section no_content message
Clicking the hits graph views hits for that date
When looking at a single day of hits, don't display a graph