Add gmaps4rails gem
Get gmaps4rails working on bikeway_segments#show, not showing the right thing yet.
Kitchen sink: Garber-Irish, kill turbolinks, SCSS.

* Implement the Garber-Irish pattern (Javascript-per-page-in-Rails) using the `gistyle` gem.
* Remove turbolinks, it was causing too many problems between DataTables and Google Maps, for no real win exactly.
* Bootstrap/Google Maps CSS compatibility fixes: use `content-box` for the map, and `min-size: none` on images
* Fix SCSS to not use sprockets, but Sass @imports instead. This allows us to use the Bootstrap mixins from anywhere.
Fix data import having bad lat/lng.

The lat/lng data was getting munged because I was using a "spherical factory" for what is a cartesian projection. It's a good thing I read up on projections, because I might not have understood that bug otherwise.
Get rid of old location model
On bikeway_segment#show, display KML on Google Maps.

Note it doesn't work on localhost since the Google servers have to actually fetch the KML. But if you go to `/bikeway_segments/2.kml` and load it in Earth you can see it works.

Tricky:

* Added `BikewaySegment#kml` method, which uses PostGIS to build a KML fragment (using st_transform). Even added an RSpec for it too (it's pretty brittle!)
* Used HTML5 data attributes to communicate the KML URL from Rails to JavaScript
* Used kml.erb to template out the KML file, yielding to the fragment from PostGIS in the middle
Merge branch 'gmaps4rails'