Implements Redis cache
Implements database cache and tests
Implements cleanup() in database cache class
Implements Redis cache
Implements database cache and tests
Implements cleanup() in database cache class
Creates cache tables
Implements test for Redis cache client
Merge branch '2014-04-01_cache' of https://github.com/nsendetzky/arcavias-core into 2014-04-01_cache

Conflicts:
	lib/mwlib/src/MW/Cache/Redis.php
Fixes Redis tests
Adapts Redis tests to circumvent timezone problems
Rearranges DB cache unit tests
Creates Predis client if not given via the constructor
Adds factory to cache infrastructure
Moves generating last seen products to process() which is called even when cached
Removes the cache entries when a product is changed
Implements caching partitioned by siteid and adapts search keys to avoid conflicts
Implements cache manager, item and proxy including tests
Implements job controller for removing expired cache entries
Minor documentation fix