Issue 5

* Adds lib folder in js to contain all dependencies
* Adds css folder
* Adds mapbox librairies in the lib folder.

Next step is to switch Google by Mapbox
Issue 5

Actually, Mapbox added a limitation on the number of POIs lately.
Let's use the free leaflet instead.

We can still change easily in the future. (Libraries are compatible)
Adds support for css in flask.

we really need to avoid duplication like that one day
Fixes typo
Issue 5

Code is now fully functional with leaflet.
Only missing element is the specialized marker that has to be created.
Adds missiing images for leaflet

Current map displayed is from mapbox, and can be updated to anything else (OSM, Google Maps, . . .).

TODO : Customize marker
Issue 5

Adds specialized satellite icon.
Also reduces the size to 32 pixel instead of 64 (it was a bit too big).
Merging issue_1 from vde and issue_5