Add pull method to models for bulk ajax fetches

`.pull` is like `.fetch` with three differences:
  * it uses jquery's getJSON (bypassing the internal spine query queue)
  * it can pull one or multiple ids from a server
  * it has straightforward success/failure callback parameters

Why all this?
Firstly, I like to pull in records quickly when needed, so I think
the internal queue is unecessary for quick gets.  Think: youtube
frontend (unlimited data with selective gets) instead of a tiny
contact DB or calendar where pagination or fully loading the
dataset makes sense.

Secondly, I'd like to pull in one or multiple items at a time.  If I
set the pull id to 1,4,5,6,7 the server can parse the special id
and return multiple results from one request.  Alternatively, a
list of multiple IDs can be passed in and they will be grabbed
individually.

Thirdly, simple callbacks make me happy.  Attaching handlers to an
extra options parameter feels like using YUI in 2006.

src/ajax.coffee

@@ -83,8 +83,33 @@ class Collection extends Base
       @all(params).success (records) =>
         @model.refresh(records, options)
 
+  pull: (ids, successCallback = null, failureCallback = null) ->
+    ids = [ids] unless $.isArray(ids)
+    xhrPromises = []
+    xhrPromises.push(@xhrPull id) for id in ids
+    $.when.apply(this, xhrPromises).then(successCallback, failureCallback)
+
+
   # Private
 
+  xhrPull: (id) ->
+    record = new @model(id: id)
+    d = $.Deferred (dfd) =>
+      jsonPromise = $.getJSON(Ajax.getURL(record))
+      jsonPromise.done (jsonObj) =>
+        newObj = null
+        if $.isArray jsonObj
+          newObj = []
+          @model.refresh obj for obj in jsonObj
+          newObj.push(@model.find obj.id) for obj in jsonObj
+        else
+          @model.refresh jsonObj
+          newObj = @model.find jsonObj.id
+        dfd.resolve newObj
+      jsonPromise.fail =>
+        dfd.reject id
+    d.promise()
+
   recordsResponse: (data, status, xhr) =>
     @model.trigger('ajaxSuccess', null, status, xhr)
 
@@ -183,6 +208,7 @@ Extend =
 Model.Ajax =
   extended: ->
     @fetch @ajaxFetch
+    @pull @ajaxPull
     @change @ajaxChange
 
     @extend Extend
@@ -193,6 +219,9 @@ Model.Ajax =
   ajaxFetch: ->
     @ajax().fetch(arguments...)
 
+  ajaxPull: ->
+    @ajax().pull(arguments...)
+
   ajaxChange: (record, type, options = {}) ->
     return if options.ajax is false
     record.ajax()[type](options.ajax, options)
@@ -205,4 +234,4 @@ Model.Ajax.Methods =
 # Globals
 Ajax.defaults   = Base::defaults
 Spine.Ajax      = Ajax
-module?.exports = Ajax
+module?.exports = Ajax

src/spine.coffee

@@ -196,6 +196,12 @@ class Model extends Module
     else
       @trigger('fetch', callbackOrParams)
 
+  @pull: (idOrCallback, successCallback, failureCallback) ->
+    if typeof idOrCallback is 'function'
+      @bind('pull', idOrCallback)
+    else
+      @trigger('pull', idOrCallback, successCallback, failureCallback)
+
   @toJSON: ->
     @recordsValues()