Log Message:
py-pygit2: updated to 1.2.1

1.2.1:
- Fix segfault in ``Object.raw_name`` when not reached through a tree
- Internal: Use @ffi.def_extern instead of @ffi.callback
- Internal: callbacks code refactored
- Test suite completely switched to pytest
- New unit tests
- Documentation changes

Deprecations:
- Deprecate ``Repository.create_remote(...)``, use instead
  ``Repository.remotes.create(...)``
- Deprecate ``GIT_CREDTYPE_XXX`` contants, use ``GIT_CREDENTIAL_XXX`` instead.