Update copyright to jQuery Foundation.

[scottgonzalez]

Legally correct copyright. See core and UI.

[agcolom]

@scottgonzalez @toddparker I believe most of the pages in the docs folder will need that change too. Then, we'll need to make the change to Wordpress as well.

@toddparker how would you like to proceed with the docs pages? I'm happy to do this if you like. If I make the changes in the copyright branch, when that gets merged into master, is it only one commit only that will need to be cherry-picked?

Also, if there are conflicts as a result of the merge, will someone be able to resolve them? (I don't know how to do that).

Thanks,

Anne

Edit: Sorry, I didn't refresh the PR window, and missed the fact that @gseguin had merged the PR ;-)
So 2 questions: will this need to be cherry-picked? and @toddparker how do you want to proceed? (if it is master only, I can do this easily). if it need to be cherry-picked, it'd be better to do it locally first and then pushed into master, so that there is only one commit... (is that correct?)