Export kml for IE9 (and safari filename fix)

This PR

- Enables kml export in IE9!
- Allows the correct naming of the kml file in safari browsers.
- Removes blob.js, which was needed for dirty safari hack that is obsolete now
- To avoid unneeded traffic, we only use the new service for 'bad' browsers

[Testlink](http://mf-geoadmin3.dev.bgdi.ch/gjn_download_kml)

It uses the service created in https://github.com/geoadmin/mf-chsdi3/pull/1141, thus this can be merged only after the chsdi3 pull request is merged. 
No specific browser, but guard against browsers not supporting it. I'd like to keep it.