Merge branch 'feature/cache'
Merge pull request #2 from nightscout/master

Merge retrospective-prediction
Improved caching headers:

Thanks to advice by Adrien de Croy I added/updated the following sample
headers.

cache-control: public, max-age=2592000
expires: Thu Jul 24 2014 17:16:14 GMT-0700 (PDT)
Arr-Disable-Session-Affinity: True
Updated README instructions
Updated nightscout.appcache
Small rework of the static server
Reworked to support Express.

Upgraded from node-static to Express, and now the site caches like a
champ!
Merge pull request #1 from brianhanifin/expressjs

Expressjs test