Support for specifying nodes for setup-baremetal

As a first step for removing the backwards compatability code in
setup-baremetal, we need it to support both the new and old styles of
specifiying nodes at the same time. To that end, add --nodes support
to setup-baremetal.

Change-Id: Ibd62b17d72032c61627f2a03624223dc979defbd
Merge "Support for specifying nodes for setup-baremetal"