Renamed the factory getCacheStorageMethods() method to getAllCacheStorageMethods(), returning all cache options in the library.
Wrote a new factory getCacheStorageMethods() method to return an array of those cache methods that are available with the current build of PHP (extensions tested, etc).
Refactored factory initialize() method to use the cacheMethodIsAvailable(), so factoring the logic for testing methods out of the factory.
git-svn-id: https://phpexcel.svn.codeplex.com/svn/trunk@83741 2327b42d-5241-43d6-9e2a-de5ac946f064
