Remove setup_requires from setup.py
Remove setup_requires from setup.py

Fixes #189
jmwri/voluptuous,SimplyKnownAsG/voluptuous,alecthomas/voluptuous,tuukkamustonen/voluptuous,divanovGH/voluptuous,alecthomas/voluptuous,tuukkamustonen/voluptuous,SimplyKnownAsG/voluptuous