(PDB-605) Pin facter requirement to 1.7.0

Puppet 3.5.1 pins to Facter 1.7.0, and whats more 1.6.x is no longer
maintained so this patch just corrects that.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #954 from kbarber/maint/stable/pin-to-facter-170

(PDB-605) Pin facter requirement to 1.7.0
Merge branch 'stable'

* stable:
  (PDB-605) Pin facter requirement to 1.7.0