add qipy wheel

[dmerejkowsky]

The problem we have is that qibuild is great at building Python extensions that depend on C++ code, but unfortunately it's not trivial to write a setup.y and then it's hard to re-distribute our Python bindings.

But not all is lost ! .whl is a standardized format, and there's a nice standalone Python package to generate them.

So why not add a command that will generate a .whl that we can later upload to Pypi ?
(We'll have to hack a few things for this to work on linux, but maybe it's worth trying ?)