refs #6201 disable some pymongo tests that fail on tokutek/mongodb
refs #6250 disable a couple of multi doc insert tests
refs #6033 re-enable some capped/rename tests in our pymongo driver
add transaction test example
Fix null pointer when decoding invalid DBRef PYTHON-532
Fix import when _cbson unavailable PYTHON-532

This ensures that we don't import _cmessage in
an incomplete state or segfault if _cbson isn't
available. If _cbson.so has been removed we fall
back to pure python.
Changelog for 2.5.2.
BUMP 2.5.2
skip test_copy_db on replsets until Tokutek/mongo#93 is fixed
Merge tag '2.5.2' from upstream

BUMP 2.5.2

Conflicts:
	test/test_client.py
	test/test_collection.py
	test/test_database.py
update transaction tests to use new 'client' instead of 'connection'
disable geo tests on replica sets
Merge branch 'master' of github.com:Tokutek/mongo-python-driver

Conflicts:
	doc/changelog.rst
	pymongo/__init__.py
	setup.py