[Geocoding] Updates on db with multiple countries

[K Rahul Reddy]

Hi,

I have updated the scripts to use -f option with pyosmium-get-changes. 
It makes the setup and imports a lot easier. I wrote a documentation 
page as suggested. I have added the scripts in Nominatim/utils/ for now. 
Should I write a cmake template for .sh files, so that these files can 
be built into the build directory?

Thanks and Regards,

Rahul