Fix alias being nil corner case

When the node's crowbar/display/alias was nil, we'd get a gsub with nil
later in the template. Use hostname as a fallback.
Merge pull request #329 from bkutil/fix_alias_nil_corner_case

Fix alias being nil corner case
fix bash/zsh prompt

without this change, it would count invisible escape chars
towards the length of the prompt and thus wrap too early
in ugly ways
Merge pull request #330 from SUSE-Cloud/master

fix bash/zsh prompt
Add support for Windows Server 2012 R2
Share Windows files among Windows version

There's no need to copy the same files in many directories.
Make it possible to use several versions of Windows at the same time

We were limited by the fact that we hardcoded the version of Windows in
tftpd.conf. Instead of doing that, we use \x in tftpd.conf which matches
the IP address of the requesting host, and with this IP address, we
create a symlink to the correct windows directory.
Fix typos in comment
Do not require patch in adk-tools and create symlinks

To avoid requiring a change in adk-tools, let's just make the
version-specific extra directories symlinks to the windows-common extra
directory.
Create windows common directory/files before version-specific files
Merge pull request #326 from vuntz/win2012r2

Add support for Windows Server 2012 R2