added importlib and types to known_standard_library, to make sure import sorting is stable for Python 2.6 and pypy
added importlib and types to known_standard_library, to make sure import sorting is stable for Python 2.6 and pypy

beniwohli/apm-agent-python,beniwohli/apm-agent-python,patrys/opbeat_python,patrys/opbeat_python,patrys/opbeat_python,beniwohli/apm-agent-python,beniwohli/apm-agent-python,patrys/opbeat_python