Don't test activerecord internals
Don't test activerecord internals

While in MRI default values kept in the `columns` array are always
quoted, in JRuby, they are resolved to the correct type. Since the
following test already checks for user expectation (correct default when
creating an object), I just removed the failing test.

ericcj/activerecord-postgis-adapter,amitree/activerecord-postgis-adapter