Generate fast compact proxy.pac  // FREEBIE

Generate a map from host -> [url_path_patterns,...] using url_list.
The shExpMatch need only match patterns for urls with same host.

Need to write a simple url parser since we cannot require("url") of
node.js. The urls2pac() was also called from inside chrome.
Merge pull request #313 from mozbugbox/pac-update

Generate fast compact proxy.pac  // FREEBIE