Auto-update support and Chrome extension

Several updates to support auto-update in GreaseMonkey
and TamperMonkey, plus converting to native Chrome
extension to support auto-update in Chrome.

- Changed @include to @match (Supported by GM 0.9.8+, TamperMonkey, and
Google Chrome)
- Added @version, @updateURL, and @downloadURL for auto-update support
in GreaseMonkey and TamperMonkey
- Added chrome/manifest.json to support packaging as a Chrome extension
- Added chrome/updates.xml to support Chrome's auto-update feature
- Added chrome/VP-Salesforce-Mod.crx Chrome extension