Update README.md - supported python versions
Update README.md - supported python versions

Python language support documentation: pyVmomi 5.5.0_2014.1 and above supports Python 2.6, 2.7, 3.3 and 3.4
michaelrice/pyvmomi,hartsock/pyvmomi,tianhao64/pyvmomi,vmware/pyvmomi,davidmontgom/pyvmomi,chenpiao/pyvmomi,serialdoom/pyvmomi,rhadman/pyvmomi,Infinidat/pyvmomi,spicykaiju/pyvmomi,higebu/pyvmomi,y12uc231/pyvmomi,alexkolar/pyvmomi,borland667/pyvmomi,virtdevninja/pyvmomi-ce,gdowding/pyvmomi