Add PostGIS

- Add gem 'activerecord-postgis-adapter'
- Enable postgis extension
- Use PostGIS to calculate nearest bike stations
Add route and station database migration

- Routes table has two belongs_to relationships with stations
-- start station && destination station
- Custom foreign key names
- Enable postgis extension
Add Route and Station models

- Route double belongs_to relationship Station
- Route is users bike route which includes origin, start station, destination station, and destination
- Station is Citibike station pull from station feed JSON
Add Routes and Stations Controllers

- Routes only new, create, show
- Stations only create - responsible for updating external Citi Bike JSON API with database
- Add controller methods to routes.rb
Merge pull request #7 from zkarst/setup_models

Add route and station models