Upgrade to jQuery 1.9.1
Replace jQuery extensions with Annotator.Util

Use of jQuery extensions was predicated on the assumption that we could
effectively isolate our modifications of jQuery from other users on the page.
This required use of jQuery.sub(), which has been deprecated since jQuery 1.7
and has finally been removed in 1.9.
util: move extant util module into extensions.coffee
util: rename "extensions" -> "util"
Merge pull request #217 from okfn/jquery19

Upgrade jQuery and replace jQuery extensions