Update language-to-array conversion migration.

The original migration didn’t properly transform the data. This one
does.
Remove unused factory.
Clean up unused code.
Add missing search params to root endpoint.
Update phone field settings and examples.

In the admin interface, increase the maxlength for the phone number
field to allow formatting styles that put parentheses around the first
3 digits.

Change country prefix examples to only include a number, without the
plus sign.
Simplify missing_template method.
Remove unused code and fix spelling errors.
Add support for Rack::Cache & Memcachier caching.
Remove staging.rb.

A separate environment for staging is not needed nor recommended. Staging apps should run in the production environment.

See these Heroku articles for more details:
https://devcenter.heroku.com/articles/multiple-environments

https://devcenter.heroku.com/articles/deploying-to-a-custom-rails-environment
Use hexdigest for cache key.

To make the cache key small. Problems can arise if the cache key is too long.
Merge pull request #280 from codeforamerica/update-caching

Update caching
Update Rails version in README.
Refactor layout_by_resource
Update rack-timeout to version 0.1.1
Update sass-rails to version 4.0.5
Add version constraint for jquery-rails.

jquery-rails 4.0 requires Rails 4.2 or above.
Remove duplication in funding_sources.js
Update coveralls dependencies.

For some reason, 0.7.2 isn't being installed when running bundle update coveralls.
Update spring to version 1.2.0
Update bootstrap-sass to version 3.3.1.0

Due to changes to bootstrap modals, I had to refactor the warning modals, which is a good thing because it got rid of a bunch of code.