Remove JQuery dependency

[uklance]

CometD have not written a full "core" javascript implementation. Instead, they have left a few abstract functions around XHR and JSON parsing. These functions have been implemented in the jquery and dojo integrations. I see that someone has also created an ext-js implementation here https://github.com/kembuco/extjs-cometd/blob/master/ext/ux/Cometd.js

It should be possible to write an implementation on top of tapestry.js (I'm just not sure I'm the man for the job)

Here are the jquery-specific files that need to be implemented:
https://github.com/uklance/tapestry-cometd/tree/master/src/main/resources/org/lazan/t5/cometd/jquery

As part of this, PushTarget.js will need to be fixed. It currently relies on jQuery.append(), jQuery.prepend() and jQuery.html()