Chrome Web Store update patch: Part II

[neocotic]

This is a followup to my previous pull request that reintroduces version information through a significant rework of getMeta. A different endpoint is now called to get the extension details as JSON. However, Google return dirty JSON so xhr.responseJSON was not viable and xhr.responseText is treated before being parsed in to JSON.

I've also included a few minor changes;

• Extension links now point at https://chrome.google.com/webstore/detail/EXTENSION_ID instead of https://chrome.google.com/extensions/detail/EXTENSION_ID.
  • I believe this was done previously for MyExtensions but doesn't seem to have been applied in source control.
• Since comments are now known as "Reviews" in the new design I changed any references to reflect this.
• Couple of spelling corrections.