Moved interface clean up to correct shell script.

Removing the MAC address from the interface configuration file is
definitely better suited for cleanup.sh instead of vmware.sh.
Removed wrongly committed ubuntu file.

This was actually not yet ready to be committed. I don't feel
like reverting.
Added comments for puppet setup.
Moved disabling requiretty stuff to a common shell script.

As disabling the requiretty stuff is needed for Ubuntu too, it's
more convenient to move this code to a common shell script instead
of duplicating the code.
Added sshd shell script to provisioner for all CentOS templates.

The sshd.sh that speeds up SSH logins was missing in all templates.
Remove bare metal templates.

Does not make much sense to have such a template.
Moved sudoers stuff to its own os specific file.

As setting up sudo settings for vagrant user is actually os
specific it makes sense to move this code its own files.
Removed pleonastic sudo change.

The user vagrant does not need to be in group wheel as there
is an entry in sudoers file to gain root privileges.
New templates for Ubuntu Server 12.04 x86_64 (precise64).

packer-templates now features two templates for Ubuntu Server release
12.04.4-x86_64.

Specialty: While rhel derivates are capable to to package upgrade during
kickstarting and therefore new kernels are loaded after first reboot,
debian derivates are doing a distupgrade right after first reboot. That
means another reboot is necessary to laod the new kernel to be able to
correctly install the VirtualBox guest additions (see
scripts/ubuntu/base.sh).