Update item_profile.py

Adds <<inherit>> to the virt-type dropdown box when editing a system or a profile in cobbler_web
Update item_system.py

Adds <<inherit>> to the virt-type dropdown box when editing a system or a profile in cobbler_web
Dont reset CONFIG_ARGS as it might have been sourced from sysconfig/defaults.

This is also a partial fix for #1141.
Merge pull request #1166 from jmaas/master

Dont reset CONFIG_ARGS as it might have been sourced from sysconfig/defa...
Next release from master will 3.0.0
Merge pull request #1167 from jmaas/master

Next release from master will 3.0.0
Ensure all variables are available in PXE generation (#505).
Merge pull request #1170 from jmaas/master

Ensure all variables are available in PXE generation (#505).
Move all unittests into ./tests/, adjust Makefile accordingly.
Merge pull request #1172 from jmaas/master

Move all unittests into ./tests/, adjust Makefile accordingly.
Merge pull request #1160 from langimike/master

Add <<inherit>> option to virt-type fields when editing a system or profile in cobbler_web
Remove mention of avahi from the cobbler manual page.
Merge pull request #1174 from jmaas/master

Remove mention of avahi from the cobbler manual page.
Support virtio26 for generic qemu fallback
More work on input validation.
Merge pull request #1181 from jmaas/master

More work on input validation.
Merge pull request #1178 from opoplawski/virtio

Support virtio26 for generic qemu fallback
Merge pull request #1155 from TheMeier/master

Debian network config: add support for tagged vlan only bonding interfaces
This is a quick and dirty fix,  about `/boot/efi/EFI/redhat/grub.efi` can not find the configuration file.
Fix pyflakes warnings in utils.py

pyflakes says, "import 'os' from line 24 shadowed by loop variable"
and breaks "make qa".