HTTPS support

Leaflet library on `cdn.leafletjs.com` is not supported HTTPS.
Every example standardized by `cdnjs.cloudflare.com` to support it.

**Old**

``` html
<script src="//cdn.leafletjs.com/leaflet/v0.7.7/leaflet.js"></script>
```

**New**

``` html
<script src="//cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.7/leaflet.js"></script>
```
