Revert "Set 'Vary: X-Request-With' to disable payload caching" [because of nette/nette@d9951817f5423a657737f9c595572da2c1f24ed2]

This reverts commit 07f03cc7dbf0ba2acb70e5c7ffc06c71fc9e8057.
Validation: event is also killed with 'return false' [closes #57]
Snippets: queues are changed to $.Callbacks() instances
History: snippets in components get cached too [closes #77]
Spinner: support for more simultaneous requests
Merge pull request #78 from matopeto/patch-1

Support for more ajax requests (in spinner extension).
History: prevented initial request in Chrome [closes #61, #64, #73]
History: cached snippets fire before, after and complete queues (thx to @daliborcaja)

http://forum.nette.org/cs/11005-nette-ajax-js-alt-obsluha-pro-ajax-s-jquery?p=11#p115566
Merge pull request #1 from vojtech-dobes/master

Update master