updated version of the classes-lessons file

Modified per Emily's suggestions
checkin of resource and image files to my branch & changes to classes-lessons file to like to index.html
renamed files and deleted bad ones
Merge remote-tracking branch 'origin/esv-work'
minor tweaks

corrected links in the index.html file (was looking for about.html)

fixed spacing/indenting in classes-lessons.html

checked for HTML5 validation errors (there were none)
minor change to subnav link names
putting in the responsive grid system
added sitstylesheet.css to index.html file