Add Geolocation for Mobile (JS)

[benjaminpick]

http://diveintohtml5.info/geolocation.html

Do this only for mobile browsers (ontouchstart)
Optional: Use "high accuracy position"

This must be optional (preferences) as it asks the user to reveal his location, and this may not be desired.

[benjaminpick]

However, we would only get the position, not a city name (maybe use Google API coding for this). Also, the lookup happens on client side and will be passed as cookie, so it is not available on first load.

[benjaminpick]

This requires the fallback #13 . In this way, the client-side code can set a cookie to indicate the results, and the server will use it on the second request.