Updated the URL for imageJ, changed from http to https.
Updated the URL for imageJ, changed from http to https.

The test was occasionally failing because the http was redirecting to
https.

zivy/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks