Updated feature: Gleez Cache_Mango v1.2.0

+ Added Cache_Mango::find - Finds cache entries based on a tag
+ Cleanup Cache_Mango::set_with_tags
+ Cleanup code
Updated feature: Added Mango driver (MongoDB) overview
Fixed issue: Amended description of the returned result
Merge pull request #511 from sergeyklay/master

Gleez Cache_Mango v1.2.0