Remove unused source code directories and files:
  + unsafe_transforms/
  + tests/
  + profiles/
  + libtransforms/piltransform.py
  + libtransforms/zope27rest.py
  + setuphandlers.py

TransformEngine.py only contains TransformTool class (and TransformTool.py is
just importing it) so rename that file to TransformTool. Also, cache module
only defines Cache class and this is only used in TransformTool so move it to
TransformTool module.