Add trailing slashes, fix broken tags, twitter https

Add trailing slashes to internal links including geeks, people, and
cities links
Fix a bunch of unmatched divs, anchors, italic, and p tags
Replace http://twitter with https://twitter
Unintentionally removed trailing white space
Merge branch 'master' of https://github.com/nathanjessen/codeforamerica.org

Conflicts:
	_includes/people/rhys-fureigh.html