Add __package_pkgng_freebsd type

Create __package_pkgng_freebsd type to handle package management via pkg-ng
Add explorer to __package to determine if "pkg" exists on the remote freebsd system
Expand logic within __package/manifest to determine which freebsd package manager to use
I guess the answer is no - but is there no obvious easier way than to filter 4 times? Can you provide a sample output and input values?