[#ONwaMmbJ] Cache static files for 1 year.

Branch: ONwaMmbJ-fingerprint-assets
add cache-control check to assets test
use extended format for year milliseconds
[#ONwaMmbJ] Don't cache assets in dev, add assets_max_age option.

Branch: ONwaMmbJ-fingerprint-assets
Merge pull request #76 from SparkartGroupInc/ONwaMmbJ-fingerprint-assets

[#ONwaMmbJ] Cache static files for 1 year.