Saner debug log message generation
Saner debug log message generation

For some reason building the debug log would include spaces in the
message elements and join on the empty string. It makes much more sense
to just build the list and join on the space.

Change-Id: Idd82787b87518c56122d0b13551f84529306337c

jamielennox/keystoneauth,citrix-openstack-build/keystoneauth,sileht/keystoneauth