Add new functionality in the case of next-server not being specified for some reason, to ask the user to enter the tftp server ip.  Update, slightly, how disks are detected using linux native methods.  Update the ipxe files for such things as well.  Will update init files as well.

git-svn-id: https://svn.code.sf.net/p/freeghost/code/trunk@2777 71f96598-fa45-0410-b640-bcd6f8691b32