Add the updated SW cache polyfill
Fixed some bugs in the polyfill
Remove the older polyfill
Upgraded Polymer dependencies to avoid conflicts
Change the way that parameters are serialised
Detect the URL of the current script so that we can refer to the serviceworker.js script.

NOTE: Kind of a hack, currently Chrome only.
Use the new polyfill, change the current strategy to 'race network and cache, use the first'