ENH: Add server URL to ArchiveTestingData script.

Allow the use of http://slicer.kitware.com/midas3/

Change-Id: Ia6e15ccc41b96f2beb2523aadcd72e6d44c47c70
Merge topic 'TestingDataServer'

c910728 ENH: Add server URL to ArchiveTestingData script.
ENH: Add slicer.kitware.com to the list of ExternalData resources.

Change-Id: If385d45f910b3a1501a7f21368b797907a1c6883
Merge topic 'TestingDataServer'

5006435 ENH: Add slicer.kitware.com to the list of ExternalData resources.