Getting rid of outdated code
Getting rid of old stuff
Porting downloader to use distlib

We're now using the distlib Locator API to find packages to download. It
will make curdling closer to the high end python package stuff and kill
a lot of code in curdling;

Regressions:

  * Curdling server is not supported anymore due to the new locator API
    thing, now the server needs to be changed to provide another
    resource listing versions of a given package which will be done
    separately;
Using distlib+wheel instead of pip to curdle packages

We no longer have to have pip installed to curdle packages, just wheel
and curdling; Now we are manually unpacking the file, finding the
special `setup.py` script and calling the command `bdist_wheel`, then
indexing the newly created file.
Fixing a small bug in the way we find the setup.py script (curdling)
Organizing a little bit more the `Service` constructor params