Fix the dhcp clean up for Ubuntu 12.04 or newer's postinstall.sh

For more info, please see the Launchpad issue at https://bugs.launchpad.net/ubuntu/+source/isc-dhcp/+bug/910108
adding an option to skip iso transfer
Added templates for CentOS 5.9 (DVD).
Added templates for CentOS 5.9 (netboot).
Accidentally deleted shutdown command.
Use thread when typing boot sequence

In some cases typing the delay in finishing the console_type method is longer than the boot process of the virtual machine. In these cases the kickstart server will only be started after the VM searches for it, which usually results in an error.

Putting the console_type method into a thread solves this problem,  as it ensures that the kickstart server starts to wait for connections before the typing is finished.

The issue has been observed with the KVM provider, but may also occur for other providers. The fix will work for all providers and does not change the current behavior.
Merge pull request #488 from ffeldhaus/build-thread

Use thread when typing boot sequence
jedi4ever/veewee#490 allocate wincp http port just before use
Cleanup rescued exceptions list; Errno::ENETUNREACH is duplicated
Merge pull request #492 from juliandunn/master

clean up exceptions list
Merge pull request #491 from hh/issue-490

jedi4ever/veewee#490 allocate wincp http port just before use
Merge pull request #442 from someara/skip_iso_transfer

adding an option to skip iso transfer
Merge pull request #428 from joneslee85/fix-precise-postinstall-dhcp

Fix the dhcp clean up for Ubuntu 12.04 or newer's postinstall.sh
Changed mirror.
Fix typo in message.
Merge pull request #495 from juliandunn/build-typo-fix

Fix typo in build message.
Correctly modify /etc/sudeors to allow passwordsless sudo.

The sed expression in the previous postinstall.sh file modifications
I had made used 4 spaces instead of a single '\t' which prevented
the required substition in the /etc/sudoers file which prevented the
vagrant user from being able to sudo without provide a password. The
sed expression now correctly substitutes the directives for the
sudo group so passwordless sudo is enabled.
Merge pull request #496 from lotia/ubuntu-sudoers-file-fixes

Correctly modify /etc/sudeors to allow passwordsless sudo.
adding "reallyminimal" boxes for CentOS 5.8 and 6.3
Merge pull request #485 from ryanc/centos-5.9

CentOS 5.9