Created originally on Bitbucket by standy66 (Andrew Stepanov)
Was already merged in Bitbucket before import, marked as merged by the import user
This is pull request for Issue #2774.
__module__ attributes to cpyext's InstanceMethod along with tests. After this modifications all tests from pybind11 master branch pass except for
test_multiple_inheritance.py. This tests are not related to instancemethod and can be addressed in different pull request.