Avoid protocol relative URLs

These fail to load in contexts where the "file protocol" is used (e.g. PhantomJS).

examples/overviewmap-custom.js

@@ -14,7 +14,7 @@ var overviewMapControl = new ol.control.OverviewMap({
   layers: [
     new ol.layer.Tile({
       source: new ol.source.OSM({
-        'url': '//{a-c}.tile.opencyclemap.org/cycle/{z}/{x}/{y}.png'
+        'url': 'https://{a-c}.tile.opencyclemap.org/cycle/{z}/{x}/{y}.png'
       })
     })
   ],

src/ol/source/mapquestsource.js

@@ -40,7 +40,7 @@ ol.source.MapQuest = function(opt_options) {
   goog.base(this, {
     attributions: layerConfig.attributions,
     crossOrigin: 'anonymous',
-    logo: '//developer.mapquest.com/content/osm/mq_logo.png',
+    logo: 'https://developer.mapquest.com/content/osm/mq_logo.png',
     maxZoom: layerConfig.maxZoom,
     opaque: true,
     tileLoadFunction: options.tileLoadFunction,