incremental, manage: do not verify if remove is safe

incremental, manage: do not verify if remove is safe

Function is_remove_safe() was introduced to verify if removing
member device won't cause failed state of the array. This
verification should be used only with set-faulty command. Add
special mode indicating that Incremental removal was executed.
If this mode is used do not execute is_remove_safe() routine.

Signed-off-by: Kinga Tanska <kinga.tanska@intel.com>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>