Fixes a styling issue with the SVG header in Firefox

There was a 1px border at the bottom of the image for some reason.
Merge pull request #19 from burlingtonruby/fix-firefox-style

Fixes a styling issue with the SVG header in Firefox
Adds twitter links to speaker profiles
Adds GitHub links to speaker pages
Merge pull request #17 from burlingtonruby/speaker-links

Speaker links
Adds Robert Jackson as a speaker