Update unit-tests and xml-docs.
Update namespaces and xml-docs.
Update xml-docs.
Add SetClockAttribute

SetClockAttribute allow to set specific date-time on Clock helper for time of test execution.
Update xml-docs

Turn-off warnings for missing xml-docs for public members as they may be inherited from base classes/interfaces.
Update xml-docs and unit-tests.

More tests for CacheBase and CacheFactoryBase