remove resource_extension and use localname minter in AT PR-61
Use generate_id branch of ActiveTriples; clean tests

* Add generate_id branch of ActiveTriples to Gemfile
* add reset method for base_uri config
* clean up tests
**  remove :3000
**  remove id_prefix
**  more fully test configuration reset
Remove FIXME comment that no longer applies

Changed code to use sub-class of Person instead of Person to avoid the problem where Person was already created with a different base_uri.