Checks that floating header is available before initializing script

- Checks for existence of floating header <div> before initializing
floating header-dependent JS.
Merge pull request #255 from codeforamerica/251-js-error

Checks that floating header is available before initializing script
Add rails_12factor gem per Heroku recommendation
Use GA script from docs instead of analytics portal

Google's docs are not in sync with the actual portal. The tracking code snippet from the portal doesn't define "_gaq", so tracking hasn't been working since "_gaq" was not defined. I just noticed the error in the console.

I switched to the code provided in the docs, which does define "_gaq", so hopefully we'll start getting some tracking data now.
Merge pull request #258 from codeforamerica/fix-google-analytics

Use GA script from docs instead of analytics portal
Add Sentry to get notified of exceptions

works with the Sentry add-on on Heroku
Disable AJAX search and links & use HTTP caching

Removed references to input-manager
Updated map links to go directly to URL instead of passing through AJAX search
Remove ajax-link class from links
Update pagination links to include request parameters
Make "kind" label in search results a link to all locations of that kind (this allows Google to index all possible locations)
Configure Dalli to serve static assets from Memcached (https://devcenter.heroku.com/articles/rack-cache-memcached-rails31)

To test caching locally:
brew install memcached

In development.rb:
config.action_controller.perform_caching = true
config.cache_store = :dalli_store
Merge pull request #263 from codeforamerica/http-caching

Disable AJAX search and links & use HTTP caching
Cleans up JavaScript modules

- removes unneeded module.
- places input-manager in unused scripts.
Offsets floating header when URL hash is present

When URL hash is present this commit causes the page to scroll up an
amount equal to the height of the floating header, so that the floating
header does not cover the result entry that's being referenced in the
URL hash.
Updates appearance of links in result entries

Consolidates link hover styles so that all links in the result entries
are underlined.
Merge pull request #264 from codeforamerica/ux-updates

Ux updates
Merges `master`