adding a caching abstraction layer to the Utron framework.

[alejandro-carstens]

Hi there,

This PR is to provide caching functionality out of the box (a cache package). As it stands at the moment the supported stores are Redis, Memcache, and map (local). This would allow for using any store interchangeably without having to change code. The api is very simple to use and rather complete, it allows for the use of tags and it also provides the ability to cache any given type of struct. In addition the code is rather extendible, if we were to add more stores we would just need to comply with the given interfaces and make the tests pass for the given store. I believe the framework could benefit of something like this given to the fact that caching is a major component for any type of application and it keeps the framework lightweight (I would say it makes it even more lightweight, decreasing calls to the db). I appreciate you taking the time to review this PR and I think what you are doing with utron is great. Please let me know your thoughts and have a nice day.

Alejandro

[coveralls]

Coverage decreased (-1.2%) to 77.764% when pulling 0261ef3 on alejandro-carstens:master into 9afa378 on gernest:master.

[coveralls]

Coverage decreased (-1.7%) to 77.295% when pulling a82bd3e on alejandro-carstens:master into 9afa378 on gernest:master.