BUG: exit with failure code when not enough arguments are specified.

Change-Id: Idea1530e305554e374e3d0c492de05044bb7fff9
Adding BSpline registration examples based on ITK DeformableRegistration4

Change-Id: Ifc6f81b4ca090b5a97e0fcd87a7dbadf1daccc2f
Merge topic 'SIMPLEITK-571_AddMoreRegistrationExamples' into next

91a8d3c9 Adding BSpline registration examples based on ITK DeformableRegistration4
57d4df52 BUG: exit with failure code when not enough arguments are specified.