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!
Full Caching with Express,

Upgraded from node-static to express.
Upgraded from node-static to Express,

and now the site caches like a
champ!
put everything in a static directory

Tested by deleting everything, running npm install from scratch.
This helps ensure that only the files in the static subdirectory can be served.
Should eliminate serving config files via http.
Merge pull request #1 from robynec75/express-cache

Express cache