[CB-7419][WP8] Added support to get metada from directory

The error CODE 1, in the callback it was about the failed attempt to get the size of a directory using 'IsolatedStorageFileStream', throwing a SystemException 'DirectoryNotFoundException'.

Instead 'IsolatedStorageFileStream' to get that information from a directory, now uses Application.GetResourceStream, to get that information from the provided path, only if directory. If other file it would use 'IsolatedStorageFileStream'.