Minor fixes for lib/baremetal

A recent patch moved the flavor management out of nova-manage
and into python-novaclient. This corrects the behaviour of lib/baremetal
so that it calls "nova flavor-key" instead of "nova-manage". This also
fixes a logical error in testing whether dnsmasq is installed.

Change-Id: I3fa821c22ae45a49e283d091b6e5ed51c9757e88
Merge "Minor fixes for lib/baremetal"