self reference in SentinelConnectionPool changed to weak reference 

circular reference changed to weak reference to enable garbage collection
Add extra info to exceptions raised in pipelines. Fixes #407

ResponseErrors generated by commands executed in a pipeline now includes the
command position in the pipeline and the actual command sent to the Redis
server. For example:

Command # 3 (LPUSH c 3) of pipeline caused error: <actual error message from
    Redis server>
Merge pull request #409 from paulovn/master

Circular reference in SentinelConnectionPool changed to weak reference, to enable garbage collection
this issue fixes #413

connections that have gotten a mismatch number of responses to requests in a pipeline should be disconnected
ConnectionPools in forked and multi-threaded environments play nicer.

Thanks Christian Joergensen. Fixes #412
Merge branch 'master' of github.com:andymccurdy/redis-py
version bump to 2.9.0
remove pytest's cache directory and *.pyc files from distribution
Merge pull request #414 from shearic/fix_badconnection

this issue fixes #413
Add IPv6 support to 2.6+.
Added timeout.
pep8, version bump to 2.9.1
Fix argument spelling
Merge pull request #429 from p/argument-spelling

Fix argument spelling
with tox/travis, tests don't need to know about the environment
Merge branch 'master' of github.com:andymccurdy/redis-py
make sure hiredis parser raises connection errors
changelog
Merge remote-tracking branch 'upstream/master'