Use Sidekiq to geolocate Visits

This is part of a move away from Whenever, partly due to the difficulty
in working with Whenever and Brightboxes, but also to try and save on
the cost of spinning a new Rails environment up everytime one of the
geolocation tasks run.
Remove empty cartodb scripts, whatever they were
A sidekiq job now handles the cartodb sync, too
Update README to reflect sidekiq job changes
Don't run geolocator is Visit is already geolocated
Sidekiq deployment tasks
Env based cartodb tables
Sidekiq configuration
Users are required to login to create and delete URLs
Remove no longer existing /map routes
Sign in user for ShortURL#create test, as now required
Test is more robust
Only owners of a short url can delete it
Only owners of a short url can edit it
ShortUrl#update action was redirecting when requested via AJAX (there is
no non-ajax form), which caused a redirect loop
Correctly use PUT and not POST for update test

This is purely semantics, POST works identically when requesting a
resource directly
Bundle update
Bundle update
Don't include secret key in repo
Use dotenv to store SECRET_TOKEN