run_geocode? rspec coverage

* Moved Sam's rspec tests to `geocode_spec.rb`
* As per Sam's recommendation, added unit tests to cover all possible branches of conditionals in `run_geocode?`.
* Reclassified my existing rspec tests as integration tests, checking that adding option `:process_geocoding => :run_geocode?` properly curtails the behavior of `acts_as_gmappable`,