Added ability to customize the OSM url

[BerryDaniel]

Feature addition #176

Added two setting variables:

var settings = {
  coordinateDisplay: coordinateDisplays.DMS,
  DDPrecision: 8,
  WFSVersion: '1.1.0',
  WMSVersion: '1.1.1',
  WPSVersion: '1.0.0',
  //Set to OsmLocalUrl to 'default' for default mapnick osm basemap
  OsmLocalUrl: 'default',
  //OsmLocalUrl: 'http://{a-c}.tile.opencyclemap.org/cycle/{z}/{x}/{y}.png',
  OsmLocalAttribution: 'All maps &copy; <a href="http://www.opencyclemap.org/">OpenCycleMap</a>'
};

OsmLocalAttribution is only used if OsmLocalUrl is not 'default'

Screenshot displays opencyclemap.org being used, instead of default mapnik.