Description of problem:
Anaconda doesn't warn user when He/She tries to use btrfs for /boot

Version-Release number of selected component (if applicable):
fc21.x86_64 workstation live

How reproducible:


Steps to Reproduce:
1.put machine in UEFI mode (without CSM)
2.initialize a disk in GPT layout to be used for instalaltion
3.boot live cd and in anaconda partitioning page make a btrfs file system for root 
4-make a "EFI system partition" for /boot/efi
5-begin installation

Actual results:
system wont boot, gives kernel panic, "can't mount VFS"

Expected results:
anaconda warn user to select a ext4 file system for /boot 

Additional info:
if I install with this layout system will boot correctly after installation:
"EFI system partition" on /boot/efi
ext4 on /boot
btrfs on /

but if I use this layout it will give me kernel panic "can't mount VFS":
"EFI system partition" on /boot/efi
btrfs on /