Merge pull request #9 from WenhuaChang/master

Support for removing /boot for btrfs
Allow change disk order for grub2

Fix YaST doesn't allow to change disk order when grub2 is choosen as
bootloader (bnc#785569)
Remove grub2 under developing warning

Remove grub2 is still under develope and test warning after user choosed
it. (bnc#780637)
Make better grub2 install summary

Make better grub2 install summary as much information as we used to have
for legacy grub.