Use FDQN attribute in Boundary namespace

`node[:fqdn]` is set by ohai and has a highest precedence and
"can not be modified" per
http://docs.opscode.com/essentials_cookbook_attribute_files.html.

This changes the bprobe name to an attribute with a lower priority
so it can be overwritten. Eg `normal[:boundary][:fqdn] = 'foo'`.
Refactor name of hostname attribute

Based on the pull request feedback...