Properly implement types

The types are not correctly implemented at all. string/varchar is just enough to pass the dbapi2 compliance test for `cursor.description`

make copies of that test that check all DB types & all dbapi2 types.

#### Resouces:
* types in this src:https://github.com/dschep/rdsdataapi/blob/99aa7bf70407a65c2eb5bdbe6088e20c2c7536b5/rdsdataapi.py#L295-L299
* types in dbapi2 docs:https://www.python.org/dev/peps/pep-0249/#type-objects-and-constructors
* `cursor.description` test in dbapi2 compliance lib: https://github.com/baztian/dbapi-compliance/blob/c259a6ab3a90db89b40936a9a36745a0a6383d5e/dbapi20.py#L245-L276