Auto update weather to current area

[Eduard Gotwig]

When the location of the notebook changes, gazette should recognize this, and update more often and show the new weather conditions.

Keep Weather ID only as an optional way to select the current area in a hard way (aka. disabling this behaviour, if location-id is specified)

IMPLEMENTATION PROCESS:

We can NOT use GeoClue in combination with Ubuntu GeoIP provider, as the data is too unreliable. In contrast to that, the Geolocation API of Webkit which follows the W3C Recommendation delivers highly accurate data (typicaly 30 meter radius)

http://webkitgtk.org/reference/webkitgtk/stable/WebKitGeolocationPolicyDecision.html

https://raw.github.com/BlankOn/manokwari/master/vapi/webkit-1.0.vapi

http://bazaar.launchpad.net/~lorenzo-carbonell/my-weather-indicator/trunk/view/head:/src/whereami.html and

http://bazaar.launchpad.net/~lorenzo-carbonell/my-weather-indicator/trunk/view/head:/src/whereami.py

are useful resources.