jQuery.support should be deprecated

There is some conversation on #451, but the gist is that we want to generally and more explicitly discourage the use of `jQuery.support`. And [according to](451#issuecomment-36518862) @dmethvin, it was an oversight that it's not already listed as deprecated.

Seeing as some plugins and frameworks, including jQuery UI/Mobile, currently rely on its existence (even if it is just to add their own internally-used properties to it), there may need to be some more intra-team conversation on the topic of if/when/how to eventually either list is as "removed" or unpublish it altogether from the API.

One immediate concern for the deprecation step is that there are references to it in the doc for [`jQuery.cssHooks`](https://api.jquery.com/jQuery.cssHooks/) that may need to be changed or removed accordingly (possibly in the same pull request?).

Thoughts?