Update localForage library to a stable version 1.0.1

This PR upgrade LocalForage to a stable version  ( add try catch at critical points : https://github.com/mozilla/localForage/blob/db6cf2ae838dc636161fc18366dcdc09f9d54db3/src/localforage.js#L74)

That also fixes some js issues in old browsers.

I also removed the use of `getTile` on desktop.

Test [here](http://mf-geoadmin3.dev.bgdi.ch/dev_localforage/)

As it's used only on mobile, we could load it only on mobile, not?