title: How can i make so that when a layer is added to a map it is added as the bottom layer in OpenLayers 3?
body: <p>I am trying to figure out a good way to switch maptypes and add the layer as the bottom layer. The other layers are information layers that should be on top always. I tried to use the map.baseLayer property but the layer is still rendered on top of the other layers.</p>
  
  <p>Here is what i got:</p>
  
  <pre><code>var OSMLayer = new ol.layer.Tile({
      source: new ol.source.OSM()
  });
  
  // Initial map
  var currentMap = OSMLayer;
  
  var mapQuestOSMLayer = new ol.layer.Tile({
      source: new ol.source.MapQuest({layer: 'osm'})
  });
  
  var mapQuestSATLayer = new ol.layer.Tile({
      source: new ol.source.MapQuest({layer: 'sat'})
  });
  var mapQuestHYBLayer = new ol.layer.Tile({
      source: new ol.source.MapQuest({layer: 'hyb'})
  });
  
  var map = new ol.Map({
    layers: [OSMLayer],
    target: document.getElementById('map-canvas'),
    view: new ol.View({
      center: [0, 0],
      zoom: 3
    })
  });
  
  // How can i set the layer as the bottom layer?
  
  $('#btnMapTypes ul.dropdown-menu li a').click(function (e) {
      map.removeLayer(currentMap);
      switch($(this).attr('data-type')){
          case 'OSM':
              map.addLayer(OSMLayer);
              map.baseLayer = OSMLayer;
              currentMap = OSMLayer;
          break;
          case 'mapQuestOSM':
              map.addLayer(mapQuestOSMLayer);
              map.baseLayer = mapQuestOSMLayer;
              currentMap = mapQuestOSMLayer;
          break;
          case 'mapQuestSAT':
              map.addLayer(mapQuestSATLayer);
              map.baseLayer = mapQuestSATLayer;
              currentMap = mapQuestSATLayer;
          break;
          case 'mapQuestHYB':
              map.addLayer(mapQuestHYBLayer);
              map.baseLayer = mapQuestHYBLayer;
              currentMap = mapQuestHYBLayer;
          break;
      }           
  });
  </code></pre>
  
  <p>What is the proper way of achieving the result im looking for? Thanks!</p>