Updated index page to come closer to current reality.

Awaiting our overall blurb.

Stored some of the old text from index.html in a text file, for a little while.

My view is that most of what we want to say will go onto the wiki rather than be here.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Merge branch 'gh-pages' of https://github.com/isetbio/isetbio into gh-pages