ESDEV-438. Static Cache. Method oxArticle::resetStaticCache is now a static method, accepts parameter to remove a single entry.
ESDEV-438. Static Cache. Added Static cache clearing to test setup and teardown in OxidTestCase.php. oxarticleTest has additional call to clear static caches at the end of setup call.
ESDEV-438. Static Cache. Removed calls to method oxArticle::resetStaticCache, because cache should be handled by oxArticle properly.