As per change https://review.openstack.org/33429 the config sections
became lowercase. This patch makes the quantum-rootwrap-xen-dom0
rootwrap to be case insensitive for the xenapi section.
This patch also changes the default config file to use a lowercase
xenapi section.
Fixes bug 1195781
Change-Id: Ic24feb1a9ad6f8823745b1febd4a0edd54e73498