Make cadquery work with FreeCAD 0.13 on py27, on Linux.

Please note: I was sleep deprived when I did this, so it may break utterly on Windows (although if it does, fixing is probably simple). It looks like FreeCAD changed their structure in 0.13 from 0.12 so that Parts and Drawings etc are all self sufficient modules instead of components of FreeCAD, which is a bit odd afaict. This may also be a bug in the master/head version of FreeCAD. This patch is a _hack_ to get things to import so I could play with cadquery, and shouldn't really be used without a rewrite (hey, it was an hour on my saturday night).

p.s. Awesome library, and way neater than CGAL to use. I have just scratched the surface bu I like what I see so far.

- This is _totally_ experimental, and I haven't done exhaustive
   tests
 - 88 unit tests do pass though, and I added a new import test.
 - 0.12 and 0.13 seem to structure stuff a bit differently,
   probably due to changes in the FreeCAD lib wrappers.
 - Not tested on windows (but should work) or 0.12. Need some
   help there.