Clean up web presence for NIFTI

[hjmjohnson]

NITRIC is still promoting NIFTI :).

It would be nice to clean up our web presence and reference the new github site as a primary source of using NIFTI effectively.

• @afni-rickr https://nifti.nimh.nih.gov (reference the github pages)
• @fissell / @afni-rickr Completely remove the sourceforce nifti site, or change all it's references to github. Deleting the CVS would be a high priority so that users are redirected to to github, and removing the outdated web page would also be high priority. Google still hits sourceforge first, therby giving outdated information.
• @afni-rickr Update the NITRIC site to reference the github resources instead of the sourceforge resources. (See email from Dec. 20, 2018 that has links to the nitric site with outdated information).