Added condition requirement to argparse

Change-Id: Ibffdcbd3ed7e2c2e982023455d60d10a6001ff23

setup.py

@@ -6,9 +6,11 @@ from setuptools import setup, find_packages
 def read(fname):
     return open(os.path.join(os.path.dirname(__file__), fname)).read()
 
-requirements = ['httplib2', 'argparse', 'prettytable']
+requirements = ['httplib2', 'prettytable']
 if sys.version_info < (2, 6):
     requirements.append('simplejson')
+if sys.version_info < (2, 7):
+    requirements.append('argparse')
 
 setup(
     name = "python-keystoneclient",