[Finder] Fixed AbstractFindAdapter for non-realpath.
[Finder] Added testcases for PHP streams.
[Finder] Fixed testcase fail message on PHP streams and PhpAdapter.
[Finder] Added directory parameter to the isSupported method of adapters.
[Finder] Added additional method canBeUsedOnPath for AbstractAdapter and optimized the isSupported cache.
[Finder] Added testcase for mixed sources (realspaths and streams) and added string casting on  for isSupported.
[Finder] Shortened isSupported method like proposed and cleaned up the testcases.
[Finder] Reworked the streams and realpaths testcase to a single one with dataprovider.
[Finder] Fixed parameter  to  for method canBeUsedOnPath of AbstractAdapter.
[Finder] Updated testcase for stream handling and done some general cleanups according to the discusion.
[Finder] Updated testcase for stream handling and done some general cleanups according to the discusion.