Fix requirements with proper versions

Author: alvarolopez

requirements.txt

@@ -12,11 +12,11 @@ oslo.concurrency>=3.20.0 # Apache-2.0
 oslo.log>=1.8.0 # Apache-2.0
 oslo.utils!=2.6.0,>=2.0.0 # Apache-2.0
 
-python-novaclient!=2.33.0,>=2.28.1
-python-keystoneclient!=1.8.0,<3.0.0,>=1.6.0
-python-glanceclient>=0.18.0
-python-ceilometerclient>=1.5.0
-python-neutronclient>=6.7.0
-keystoneauth1
+python-novaclient>=2.28.1 # Apache-2.0
+python-keystoneclient>=3.0.0 # Apache-2.0
+python-glanceclient>=0.18.0 # Apache-2.0
+python-ceilometerclient>=1.5.0 # Apache-2.0
+python-neutronclient>=6.7.0 # Apache-2.0
+keystoneauth1>=3.4.0 # Apache-2.0
 
 stevedore