Tile doesn't display if the notebook folder is called 'notebooks' or 'voila'

[12rambau]

As referenced in (sepal_ui #35)[https://github.com/openforis/sepal_ui/issues/35], Local raster images are not being displayed in voilá dashboards nor Jupyter SEPAL dashboards, the problem comes up when the xarray_leaflet module is stating the base_url, using the 'notebooks' word.

The sepal module dashboards are being stored in /shared/notebooks/, so the condition is trying to find the last 'notebook' word, but as there are two occurrences in the URL, it will take the second, causing confusion and pointing to nowhere.

[dfguerrerom]

I thought it was fixed with #25. Thanks.