Upgrade jQuery to 1.10.2

* Upgrade jquery-rails and pin version to match admin gem
Upgrade jQuery UI

* From version 1.8.20 to 1.10.4 (2 years of updates)
* Include only the sortable UI and its dependencies (core, widget,
mouse)
* Necessary so that it works with latest version of jQuery (ie
.browser() has been removed, which it was previously using)
Change detection of checked checkbox

* If the checked attribute hasn’t been set, then later versions of
jQuery return “undefined” for .attr("checked")
* Switch to a more explicit check, .is(“:checked”)
Change checkbox values using prop()

* With `.prop()` we can pass in true or false, rather than a “checked”
string
Merge pull request #206 from alphagov/upgrade-jquery

Upgrade jQuery