To help support different operating systems. Add the ability to specify a different keyword for the kickstart file. So instead of 'ks' being the only specifier for a kickstart file be able to specify a different keyword.

Propose to use 'ks_keyword'

Add a new 'ks_meta' variable 'ks_keyword'. This can be used to change
the default kickstart keyword from 'ks' to something else.

For example to support Debian can use:
  ks_meta="ks_keyword=preseed/url'

Then normal template processing will occur but instead of the kernel
command line argument being like:
    ks=http://example.com/kickstart/23

It would be:
    preseed/url=http://example/com/kickstart/23