Remove unused common.base module
Remove unused common.base module

Base module is already replaced with a module from oslo common code,
but was not removed. This patch must fix this.

Change-Id: I8f5c4da8884db4024d47ca8d1a80dbb648922a31

rdo-management/python-heatclient,jasondunsmore/python-heatclient,metacloud/python-heatclient,jasondunsmore/python-heatclient,rdo-management/python-heatclient,metacloud/python-heatclient,openstack/python-heatclient,tcpcloud/python-heatclient,varunarya10/python-heatclient,varunarya10/python-heatclient,ecerulm/python-heatclient,ecerulm/python-heatclient,tcpcloud/python-heatclient