Manifest version 2 and CSP

[neocotic]

Update the manifest to version 2 and raise the minimum Chrome version to 18 in order to be compatible with this change. Make all the necessary changes to the manifest to support the new version, including the updates to support the new default Content Security Policy. This change will mainly involve wrapping all CoffeeScript code in a DOM-ready wrapper function;

# With jQuery
$ ->
  # ...

# Without jQuery
document.addEventListener 'DOMContentLoaded', ->
  # ...

This adds no points to style but is the easiest/best way to implement this. All inline <script/> elements and event attributes (e.g. onload, onclick) will also need to be abstracted to the corresponding CoffeeScript file.

[neocotic]

I've missed something obvious here. Since only the init() method of the page scripts (e.g. background, options, notification) need to be executed when the DOM is ready, then each script should now include it's own call to init(), wrapped in the appropriate event handler.

For simplicity, I'm tempted to create a new utils.ready(handler) method that binds the function argument to either DOMContentLoaded or $.ready depending on whether or not jQuery is available;

utils.ready = (handler) ->
  if jQuery?
    jQuery handler
  else
    document.addEventListener 'DOMContentLoaded', handler

For example, the script for the background page would now include the following at the end of it;

utils.ready ->
  ext.init()

[neocotic]

I've had to add workaround fixes for the oauth2-extensions library and UserVoice widget. There's already a pull request for the first and I've made UserVoice aware of their compatibility and they're now looking into it.