Added walk funtion to allow walking the URI like a file system.
Use Python 2.x syntax (instead of yield from) for compatibility.
Add topdown to walk.
Convert references to top into references to self.
Add listdir funciton to ArtifactoryPath. Pass through to _ArtifactoryAccessor.listdir.
Add walkfilter function for filtering results and yielding one node at a time.
Add pattern_match function to support filtering on fnmatch patterns.
Removed walkfilter and related.
Merge pull request #4 from ChipJust/master

Added walk funtion to allow walking the URI like a file system.