Use utils.convert_str to convert HTTP header values
Use utils.convert_str to convert HTTP header values

This patch removes duplicate code between wsgi.py and utils.py modules.

Change-Id: Ic3eefc2bc28ff202324e7859102b289aac7974d4

Nexenta/cinder,NetApp/cinder,openstack/cinder,Datera/cinder,mahak/cinder,bswartz/cinder,NetApp/cinder,mahak/cinder,phenoxim/cinder,eharney/cinder,cloudbase/cinder,ge0rgi/cinder,Hybrid-Cloud/cinder,j-griffith/cinder,bswartz/cinder,Nexenta/cinder,Hybrid-Cloud/cinder,Datera/cinder,phenoxim/cinder,cloudbase/cinder,openstack/cinder,j-griffith/cinder,eharney/cinder