Fix passing of TESTENV_ARGS
Fix passing of TESTENV_ARGS

Bash was doing some weird things with the quoting of this variable,
so we need to wrap the whole call in an eval.

Change-Id: I596f1762e0f4685458933efdbc4d3ea26981fdd4
bz: https://bugzilla.redhat.com/show_bug.cgi?id=1228419

bcrochet/instack-undercloud,eprasad/instack-undercloud,dmsimard/instack-undercloud,dpkshetty/instack-undercloud,rdo-management/instack-undercloud,rdo-management/instack-undercloud,eprasad/instack-undercloud,dmsimard/instack-undercloud,bcrochet/instack-undercloud,dpkshetty/instack-undercloud