Deal with multiple results for automatic geocoding.

When automatic geocoding on save for a content item results in
more than one match, choose the first one and display a message
to the user that he might want to change it.

![multiple_geocoding_results](https://f.cloud.github.com/assets/405124/286975/806fddac-924b-11e2-8969-5ee3cc89e5e4.png)