ufForm should have methods to change request url, type, and dataType

[alexweissman]

Right now we are relying exclusively on the form attributes to set these values. ufForm should expose methods to dynamically change these - rather than having to go through the convoluted and slow process of modifying them in the DOM and then read them back from the DOM.

[alexweissman]

I'm working on a refactor of ufForm which will fully expose the ajax parameters through the settings, while remaining backwards-compatible.

[alexweissman]

Related: #717