Fix test_index_2dsphere for latest MongoDB

2.5 shows 'S2Cursor: BtreeCursor geo_2dsphere multi' in the explain output, not just 'S2Cursor'
Fix PYTHON-509, rare connection leaks in Python <= 2.7.0
Remove unused ThreadIdent.get() call PYTHON-509
Add test_ha and the slow tests to release instructions PYTHON-509
Update release instructions
Wrap paragraphs in release instructions
Hide slow unittests from Nose by default PYTHON-509
Fix misc. $options issues in json_util PYTHON-510
PYTHON-509 we need to synchronize the threadlocal for Python <= 2.7.0, not 2.7.1
Ensure ThreadIdent's lock is always released; improve comment PYTHON-509
Fix test_safe_update for mongo 2.5 nightly.
Merge branch 'master' of git://github.com/mongodb/mongo-python-driver into PYTHON-436

Conflicts:
	test/test_pooling_base.py
Merge branch 'master' of git://github.com/mongodb/mongo-python-driver into PYTHON-436