Fixes https://github.com/Vizzuality/re3#30
Merge branch 'gh-pages' of github.com:re3hackathon/re3hackathon.github.io into gh-pages

* 'gh-pages' of github.com:re3hackathon/re3hackathon.github.io:
  Adds hover styles for links. Closes https://github.com/Vizzuality/re3/30