feat(jqLite): implement the `detach` method

We at Angular UI are missing jQuery's detach:

angular-ui/bootstrap#1403 (comment)

https://github.com/angular-ui/bootstrap/pull/1391/files#diff-e8665eb306ddd26399e5b80f00dae5bbR252

Thanks.
jQuery returns the original element with all the nodes so jqLite should do the same. This code is fine.