Squashed commit of the following:

    commit 986ee6a73f63555048185d105d80f3c39dc7dd0b
    Author: aCandidMind <opensource@candidminds.com>
    Date:   Thu Dec 19 06:25:33 2013 -0500

        The essential differences between create and update are now reflected
        when submitting the form. They are the HTTP verb and the form fields.
        Previously they weren't because Spot#isNew() wasn't working correctly.
        Spot#isNew() works now by deciding based on the presence of an id
        attribute. MapView#addSpots doesn't add the spots collection to its
        collection any longer, but rather the models of the spots collection.

    commit fb89652cb608dd8ef689e5c35da6f955eb7231bc
    Author: aCandidMind <opensource@candidminds.com>
    Date:   Thu Dec 19 08:49:23 2013 +0100

        Form: differentiate between create and update spot.

    commit 3a76d894077bc143fad59fcee820506f1b69f9c9
    Author: aCandidMind <opensource@candidminds.com>
    Date:   Thu Dec 19 08:29:09 2013 +0100

        jquery.iframe-transport doesn't use headers set during the ajaxSetup
        so don't let it appear as if it was.