(FACT-597) Require net-tools for RHEL 7+ and Fedora 19+

RHEL 7 deprecated the use of ifconfig, needed by the interface facts.

Also removed duplicate entry for ruby >= 1.8.7
Merge pull request #730 from treydock/FACT-597/master/el7_package_dependencies

(FACT-597) Require net-tools for RHEL 7+ and Fedora 19+