Add a test SpatialModel class

* With default database config
Simplify BasicTest

* Do not use RGeo::ActiveRecord::AdapterTestHelper
* Add #test_arel_visitor
Test against AR 4.2.0.rc1
Require rgeo-activerecord 2.0
Add byebug in development
Update AR test dependency to 4.2.0.rc1
Remove unnecessary constant modification

* This is now done in register_type_map
Force create tables in tests

* Replace hashrockets