QA:Testcase btrfs installation on RAID

= Description = | Put btrfs filesystem on RAID device.

= How to test = |
 * 1) Boot the installer.
 * 2) Create /boot as ext4, swap and at least two RAID partitions. Put / as btrfs filesystem on RAID device.
 * 3) Ensure installation is finished successfully.

= Expected Results = |
 * 1) Mount point can be assigned to btrfs filesystem.
 * 2) Installation completes successfully.
 * 3) System starts properly with all filesystems mounted.