1. Add: Exit if connection to redis server failed

1. Add: marshal with type check version. This saves allocations and time if existing data is string or []byte.
2. Fix: Typos.
3. Add: Benchmarks for marshal and marshalWithTypeCheck

1. Add: Check redis connection on setup

1. Add: Save by adding provided prefix.
2. Add: Set() method will add default expiration time.

1. Add: Purge redis cache

1. Fix: panic in redis cache object is nil

1. Add: Redis as a cache support for grid mode. Redis implements cacher interface.