Changelist:

• Fixes #8 - The same cache store should't be added multiple times to the cache stores list

Changelist:

• Configure request_caching to only read from memory [#6]
• Added remoteCacheStatus class to obtain the first healthy redis node from an upstream [#7]

• Multi-layered cache support.
• Local store cache via shared dict.
• Redis store cache via lua-resty-redis
• Request caching via srcache-nginx-module