Experimental patch: Separate quick render of html from slower javascript execution

SanitizingGadgetRewriter neuters a gadget by removing all css, all javascript and those html tags that aren't on its whitelist.  This is used "to create a simple badge like display" useful when low latency and inactive content is require - for example for a view with many gadgets.

This patch provides a lower latency alternative for caja gadgets.  It:
* immediately renders the html and inline css portions of a gadget creating the "badge like display" SanitizingGadgetRewriter does
* adds a button to the top of the gadget which when clicked "rehydrates" the gadget and executes all the javascript and renders remaining css styles

[Jasvir, 2010-01-25 00:19:40]

* patch currently contains the http://codereview.appspot.com/194041/show - I'll
snapshot to remove that once its committed.  The interesting changes are only in
caja/taming.js

[Jasvir, 2010-01-25 00:22:33]

http://codereview.appspot.com/194049/diff/1/9
File features/src/main/javascript/features/caja/taming.js (right):

http://codereview.appspot.com/194049/diff/1/9#newcode124
features/src/main/javascript/features/caja/taming.js:124:
___.setNewModuleHandler(delayedLoader);
Using the delayedLoader vs the immediateLoader decides whether the gadget
javascript is executed immediately or not.  Suggestions welcome about how a
container can configure this perhaps depending on what view of the gadget is
being rendered.