Bing Map version[ Improvements ] 1.7.0.0
1.Improve my location accuracy.
2.Add a refresh button if user search driving from current location. This way user can easily refresh the routing when his location changed.
Bing Map version[ Improvements ] 1.6.0.0
1.当定位服务不可用时，默认使用用户上次退出时的地点。
2.修正地图图层问题。
1.When location service is not available, use user’s last map center to display map.
2.Fix map tile issues.
