Use same preseed file for all Debian 7 releases

The files were and most probably always should be identical.
Add packer templates for Debian 7.4
Update Debian 7.2 and 7.3 default mirror URLs

They are now archived after Debian 7.4 release.
Use builder specific output directories also for Debian 7.3 and 7.4
Remove old Debian 7 update releases
Rename Debian 7.4.0 to Debian 7.4

The official version is "7.4" even though the download URL uses the
extra digit.
Merge pull request #164 from tmatilai/debian-7.4

Add Packer templates for Debian 7.4
Fedora 18 is End-of-Life. https://lists.fedoraproject.org/pipermail/announce/2014-January/003194.html
Moved Fedora 18 and Debian 7.2 to EOL list
Merge pull request #168 from juliandunn/eol-oses

End-of-life: Fedora 18 and Debian 7.2
Updated to OmniOS r151008j
Merge pull request #169 from juliandunn/omnios-r151008j

Updated to OmniOS r151008j