OpenBSD 6.2 & 6.3 facts

[bodgit]

This PR adds facts for OpenBSD 6.2 & 6.3, fixing #71 (I don't see the point in trying to maintain anything older than the current and previous releases as they're not supported).

Facter versions < 3 are all covered and also the version that is natively provided as packages, which is 3.8.x and 3.10.x for 6.2 & 6.3 respectively.

This seems to have been the first instance of 3.10.x being included and found a small bug in the get_facts.sh script; using facter --version | cut -c1-3 doesn't work for 3.10.x (chopping it to 3.1), so something like facter --version | cut -d. -f1-2 works a bit better.

[coveralls]

Coverage remained the same at 75.0% when pulling 8d6f9e6 on bodgit:openbsd into b1bda1f on camptocamp:master.

[rodjek]

Thanks @bodgit!