Integrate GoogleMaps geocoding

[ayastreb]

As a user I should be able to use GoogleMaps geocoding For example, following post:

---
title: Paris is cool
location: Paris, France
--- 

France is nice!
{% google_map on_page %}

should geocode "Paris, France" to latitude/longitude coordinates and display it on the map.

[rriemann]

normally, you would do geocoding only ones when you render your files to HTML and not on every webpage loading.