Properly implement types

[dschep]

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:

  rdsdataapi/rdsdataapi.py

  Lines 295 to 299 in 99aa7bf

  	STRING = "varchar"
  	BINARY = bytes
  	NUMBER = numbers.Integral
  	DATETIME = datetime
  	ROWID = int

• 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

[dschep]

Started in 03dd66b

More PostgreSQL types: https://www.postgresql.org/docs/9.5/datatype.html#DATATYPE-TABLE

Need to test MySQL too.