Test configuration consistency

Remove some of the duplication in RedisClient and ClientManager
construction.  Change locations with hard-coded "localhost" or
"127.0.0.1" server addresses to use TestConfig.SingleHost.

With these changes, we're down to 10 failures(not connection-related) when
running the tests without a local instance of Redis
Getting rid of RedisTestClientManagerFactory

Moving functionality into TestConfig, per suggestion from @mythz
Merge pull request #151 from HookedMediaGroup/test_connection_string_centralization

Test configuration consistency