continuing feature improvements

[JosuaKrause]

• better lingering pipeline handling
• allow script calls in pipelines
• add "when you find a bug" to readme
• infer redis mode
• communicate inferring redis mode
• allow access of raw connections
• fix deleting and recreating in pipeline bug
• handle redis error handling better
• test multiple executes per pipeline
• test hgetall hvals hkeys
• write individual function tests using redis main object
• write docs
• add changelog file
• enforce docs via pylint
• write about how redipy can be used for testing
• add logo