OpenStreetMap to OSM renaming

OSM is a well-known name, and is shorter than OpenStreetMap.

examples/animation.js

@@ -5,7 +5,7 @@ goog.require('ol.animation');
 goog.require('ol.easing');
 goog.require('ol.layer.TileLayer');
 goog.require('ol.projection');
-goog.require('ol.source.OpenStreetMap');
+goog.require('ol.source.OSM');
 
 
 var london = ol.projection.transform(
@@ -29,7 +29,7 @@ var map = new ol.Map({
   layers: [
     new ol.layer.TileLayer({
       preload: 4,
-      source: new ol.source.OpenStreetMap()
+      source: new ol.source.OSM()
     })
   ],
   renderers: ol.RendererHints.createFromQueryData(),