Implement get_keyword_types for non parameterized types

[iDentitY4]

Implemented #83 When a type is parametrized like List, Union, Tuple, Literal then the type info is removed. See #84

Python 2 support should be working, but i didn't test it yet. The import of get_type_hints will fall back to __annotations__ on below python 3.5. On python 2 if no robot_types is set then types will be empty.