add: Fix element type

Closes gh-606
Fixes gh-309
toggleClass: rename 'switch' variable

Closes gh-610
Fixes gh-581
jQuery.ajax: Document contentType false

Added Boolean as a type for contentType.
Added a sentance about what passing false does for contentType

Ref gh-547
Ref gh-369
parent: Clarify wording about behavior

Fixes gh-537
Ref gh-543
trigger: add some links to triggerHandler
triggerHandler: Rephrase description and differences from trigger
deferred.progress: Accepts multiple arguments

Closes gh-568
jQuery.when: Update to "Promise-Compatible"

Based on gh-567 the returned value of $.ajax() is actually a Promise-compatible object and not a Promise object.

Closes gh-574
Ref gh-567