Added Tests. Combined RedisIgbinary & RedisPubSubSerialize.

Added tests:
    - IgbinaryTest, ensures igbinary extension is available.
    - RedisIgbinaryTest, ensures set,get,exits & delete works.
    - RedisPubSubTest, ensures set & get throw an exception.

Modified:
    - Core, Removed redisPubSub.
    - Factory, Removed redisPubSub constructor.
    - RedisIgbinary, publish & subscribe methods are available
        again, they just pipe through to redisPubSubSerialize
        instead of throwing an exception. Also made final.
    - RedisPubSubSerialize, made final.
    - CommandParse, isThreadKeyValid returns a boolean.
Added Core & Factory tests.

Added:
    - CoreTest, ensures Core::redis returns an instance of Redis.
    - FactoryTest, same.
    - RedisPubSubTest, fixed class name.
Created README.md