* Added interface for cache provider and service.
* Added memory implementation for cache provider (MemoryCacheProvider) and service (MemoryCacheService).
* Refactored several test cases to use mixin behavior for mock logging and config support.
* Refactored many test cases to force call of setUp() & tearDown() via super() calls.
* Refactored several test cases to check for presence of abstract service / provider variables during setUp().