Fix Open Source License classification
Fix Open Source License classification

Sets the license field to a real pypi descriptor.

closes https://github.com/vmware/pyvmomi/issues/133

michaelrice/pyvmomi,spicykaiju/pyvmomi,rhadman/pyvmomi,higebu/pyvmomi,davidmontgom/pyvmomi,Infinidat/pyvmomi,vmware/pyvmomi,gdowding/pyvmomi,hartsock/pyvmomi,serialdoom/pyvmomi,alexkolar/pyvmomi,chenpiao/pyvmomi,virtdevninja/pyvmomi-ce,y12uc231/pyvmomi,borland667/pyvmomi,tianhao64/pyvmomi