Merge pull request #35 from scub/master

Updating firewall rules
updated modified dates on ipv6 guides changes in PR #35
Update owncloud-debian-7.md

The line that needs to be added to /etc/apt/sources.list.d/owncloud.list was missing.
fix excerpts in nagios guides
Changed instances of networking to ifdown/ifup, also changed ifconfig to iproute2 as ifconfig is deprecated.
Changed review/edit dates
Update archiving-and-compressing-files-with-gnu-tar-and-gnu-zip.md

fix the tar with gzip compression command excerpt
Merge pull request #37 from capecodrailfan/patch-1

Fix Missing Package List Line in OwnCloud Guide for Debian 7
Merge pull request #38 from displague/fix_nagios_excerpts

fix excerpts in nagios guides
Changed modified by name to match
Merge pull request #39 from drussell393/master

Changed instances of networking to ifdown/ifup