valid networking facts in 2.x get ignored in 3.x

Certain hiera entries which rely on calling Facter to fill values in PE 3.8 fail miserably in PE 4.8.1.

We traced it to a behavior in Facter. Specifically, we found that calling the fact key of "ipaddress_eth0_1" used to return a good value in 3.8, but now returns a blank in puppet 4.8.1. However, I have discovered that calling ipaddress_eth0:1 in 4.8.1 does work. I was not aware of this change until one of my teams and I found out the hard way.

To test locally, one only needs to do this (as root, on any Linux server with bonding set up):

1. facter ipaddress_bond0_1
   (this should return a blank in 4.8.1, yet return the ip address value of bond0:1 in 3.8)

1. facter ipaddress_bond0:1
   (this should return an ip address that corresponds to bond0:1, and this is the workaround we put into the hiera .yaml file.)

(There may be documentation somewhere that already describes this, but I was unable to find it).