Description of problem:
ssm -f should answer y to interactive questions, but it doesn't work when in create or add command when removing device from existent pool

Version-Release number of selected component (if applicable):
system-storage-manager-0.2-2.el7

How reproducible:
Always

Steps to Reproduce:
1. setup loop devices with dd (/dev/loop0, /dev/loop1, /dev/loop2)
2. ssm add /dev/loop{0,1,2}
3. ssm -f create -p pool2 /dev/loop1
4. ssm -f add -p pool3 /dev/loop2

Actual results:
ssm still ask user to confirm whether remove device from another pool when use create or add command

ssm -f create -p pool2 /dev/loop1
Device '/dev/loop1' is already used in the 'lvm_pool'! Remove (N/y/q) ? N
Device '/dev/loop1' can not be used!!
"Error (2001): Device '/dev/loop1' can not be used!!"

ssm -f add -p pool3 /dev/loop2
Device '/dev/loop2' is already used in the 'lvm_pool'! Remove (N/y/q) ? N
No devices available to use for the 'pool3' pool!
Traceback (most recent call last):
  File "/usr/bin/ssm", line 33, in <module>
    sys.exit(main.main())
  File "/usr/lib/python2.7/site-packages/ssmlib/main.py", line 1485, in main
    args.func(args)
  File "/usr/lib/python2.7/site-packages/ssmlib/main.py", line 1008, in add
    PR.check(PR.NO_DEVICES, args.pool.name)
  File "/usr/lib/python2.7/site-packages/ssmlib/problem.py", line 275, in check
    raise exc(message)
  File "/usr/lib/python2.7/site-packages/ssmlib/problem.py", line 108, in __init__
    super(NoDevice, self).__init__(msg, errcode)
NameError: global name 'NoDevice' is not defined


Expected results:
Devices should be removed without confirmation and used to create the new pool

Additional info: