new port: sysutils/facter

Facter is Puppet's cross-platform system profiling library.

While former versions (sysutils/rubygem-facter) were written in Ruby, this
version is written in C++11. FreeBSD support in the upstream sources is
sparse and DragonFly is not supported at all for the moment.

WWW: https://puppetlabs.com/facter

Reviewed by: mat
Differential Revision: https://reviews.freebsd.org/D3579