add geometry column to sites RM-1694

- Add geometry column to sites, initialized with data (lat, lon, masl)
[masl == elevation]
- All sites are set to have srid/espg=4326 (WGS-84)
- Need to switch database.yml to use postgis instead of postgresql
improvements to spatial code

- add index to geometry
- use centroid if not a point
- remove activerecord-postgresql-adapte, is replaced by
activerecord-postgis-adapter
add comment about 4326
Merge branch 'master' into RM-1694-geometry-column
Merge branch 'master' into RM-1694-geometry-column
Updated Gemfile.lock and updated sites fixture to work with updated
table definition.
Merge branch 'RM-1694-geometry-column'
Make tests use capybara-webkit by default.  Made new environment
test_no_js for users who don't want to use the webkit.  So "test"
replaces "test_js" and "test_no_js" replaces "test".