use redis-sentinel library
better wording/formatting for persistence.test.js
connection tests

- Test that connection helper caches connection based on configs
- Test that connection.establish() times does not create many clients.
setup our own redis for connection testing
make connection methods async
use sentinel to get at the master
a changelog
setup our own redis
master failover test
connection propagates errors through callback
Connection simply throws an error
connection throws errors
delete connections always
Merge pull request #3 from zendesk/vanchi/use_redis_sentinel

Vanchi/use redis sentinel