Embed self-contained javascript

using self-contained javascript offers several improvements:

 * powertop html report can be viewed offline
 * less overall javascript code is loaded when online
 * no opportunity for report leakage or modification by third parties

These changes also make it simpler to update the html report when a
new section is added: just add a new entry to powertop.blocks
dictionary, with the section's human-readable string as its value.