Wheel check was breaking tests. Removed it.

setup.py

@@ -59,9 +59,6 @@ version = get_version('rest_framework')
 
 
 if sys.argv[-1] == 'publish':
-    if os.system("pip freeze | grep wheel"):
-        print "wheel not installed.\nUse `pip install wheel`.\nExiting."
-        sys.exit()
     os.system("python setup.py sdist upload")
     os.system("python setup.py bdist_wheel upload")
     print("You probably want to also tag the version now:")