add removeData() method to data module

closes madrobby#383

src/data.js

@@ -56,4 +56,12 @@
       // set value on all elements
       this.each(function(){ setData(this, name, value) })
   }
+
+  $.fn.removeData = function(names) {
+    if (typeof names == 'string') names = names.split(/\s+/)
+    return this.each(function(){
+      var id = this[exp], store = id && data[id]
+      if (store) $.each(names, function(){ delete store[camelize(this)] })
+    })
+  }
 })(Zepto)

test/data.html

@@ -143,6 +143,33 @@ <h1>Zepto data() tests</h1>
         t.assertFalse(el.data('bool'))
       },
 
+      testRemoveData: function(t){
+        var el = $('<div data-foo=bar />')
+
+        el.data('foo', 'bam').data('bar', 'baz')
+        el.removeData('foo').removeData('bar')
+        t.assertEqual('bar', el.data('foo'))
+        t.assertUndefined(el.data('bar'))
+
+        el.data('uno', 'one').data('due', 'two')
+        el.removeData('uno due')
+        t.assertUndefined(el.data('uno'))
+        t.assertUndefined(el.data('due'))
+
+        el.data('one', 1).data('twoThree', 23)
+        el.removeData(['one', 'two-three'])
+        t.assertUndefined(el.data('one'))
+        t.assertUndefined(el.data('twoThree'))
+      },
+
+      testRemoveDataNoop: function(t){
+        var empty = $(),
+            vanilla = $('<div />')
+
+        t.assertIdentical(empty, empty.removeData('foo'))
+        t.assertIdentical(vanilla, vanilla.removeData('foo'))
+      },
+
       testSettingDataWithObj: function(t){
           var el = $('#data_obj')