Show one photo per hour for each day

I think this is much more useful than showing all the images for a given
day.
Add recap to Gemfile
Deploy using Capistrano and recap

I've run `cap bootstrap`, `cap deploy:setup` and `cap deploy` to get the
app up on my AWS instance.
Redirect /days to the current day
Use resource rather than custom path
Route to the current day by default

I think this is better than showing /images by default.
Link to next and previous days
Use whenever to define cron jobs

I'm starting with the move_images task to make sure it works as I
expect.