COMP: CMake change that ensures ITK required modules are on.

SimpleITK assumes specific ITK modules are on, ensure this is the
case when using a system ITK, if it is not, issue a cmake error.

Change-Id: I9fdc9db93744d60fb3ed2a96e588bb636d3012be
Merge topic 'SIMPLEITK-586' into next

046f18ce COMP: CMake change that ensures ITK required modules are on.