Merge pull request #1 from jaffee/master

return false if path doesn't exist in isDirectory
merged pull request; updated hadoop isFile to reflect isDirectory; changed hadoop API call from isDir to isDirectory
Updated from getPath to getFullPath retaining the leading prefix
Update CacheRegistry.java

updated list function to always return some form of list, empty or otherwise
don't show _COPYING_ files
hopefully take care of indent issues