Index.html updated with new version correcting bugs in HTML and improperly formed Alt tags on IMG placeholders

HTML is corrected for mal formed HTML, which I spent hours trying to
debug myself and later I found that the class had found a similar bug.
Added grader.js from HW3

An exercise I forgot but I typed in the code and created the requested
file
Merge branch 'develop' into staging

Conflicts:
	index.html