Rename resource to reflect new cookbook name

This cookbook has changed names, and therefore, calls to the resource
baremetal_node shoudl reflect that change. This change only affects
how the resource is called, and nothing more.
Fix typo and ensure params are passed as strings

The first fix here is simply to rename 'res' to 'new_resource'. This
was an artifact of some older code that had been here.

The second change is to ensure that all parameters are shelled out as
strings (instead of their native integer, bool, whatever).
Make pxe ownership configurable

Thuis change makes it possible for nova to be able to write the
appropriate /tftproot, /tftproot/pxelinux.cfg, or whatever the
confoguration may call for.