CacheManager to allow retrieving Configuration instances and defining configurations based on any existing config

Enhance CacheManager API so that we can define configurations based on named caches other than the default one and also a way to retrieve Configuration instances from CacheManager without starting the cache:

So, redefine defineCache methods as:

Configuration defineConfiguration(String configurationName, Configuration overrides)
// registers and names a NEW configuration, based on the default cfg and the overrides passed in

Configuration defineConfiguration(String configurationName, String templateName, Configuration overrides)
// registers and names a NEW configuration, based on an existing, predefined configuration and the overrides passed in