BUG: Fix ResampleAnImage example (Python3)
BUG: Fix ResampleAnImage example (Python3)

Since Python 3, the division operation returns a float,
even if both operands are integers.

The setitem method from the Index class expects a long type,
so explicitely casting the result of the division to int allows
to run the example with Python3.

Change-Id: Ieeaa7e761407a61f56f5fc4118bbe77a1b358bf1

InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples,InsightSoftwareConsortium/ITKExamples