Add more tests for maxTimeMS PYTHON-550
Fix a gridfs test on Windows.
Unused import.
Improved testing for max_time_ms, PYTHON-550.
Skip test_max_time_ms_getmore on servers before 2.5.3.
Additional Bulk API testing, PYTHON-630.
Style.
Omit nModified field from Bulk API results if legacy server, PYTHON-647.
Verify reporting of nModified from collection.update(), PYTHON-648.
More reliable test_multiple_error_unordered_batch.
Test parallel_scan more thoroughly, PYTHON-633.
test interaction of w, j, and fsync options test for getLastErrorDefaults interaction
Prevent possible ref cycle in Python 3, PYTHON-646.
Avoid ref cycle in MongoClient.
Factor out oid_generated_on_client test utility.
Bulk operations raise OperationFailure, not BulkWriteError, if write concern is invalid.
Test that _id is generated on client for Bulk API insert.
Fix test_write_concern_failure_ordered for 2.6.
Race condition in GridFS test.

test_gridfs_secondary_lazy asserts that get_last_version on a secondary raises
NoFile. This fails if setUp()'s dropCollection command hasn't yet replicated:
there's still a file on the secondary.
Update ssl_match_hostname PYTHON-650

This brings us in sync with the code shipped in CPython 3.3.5.