Split geovalidate.sh into install and update scripts.

Split geovalidate.sh into install.sh and update_gadm_data.sh scripts.
The install.sh script creates the databse and uses the install sql
scripts to create all required tables.
The update_gadm_data.sh script downloads the GADM data and creates the
gadm2 table from the shape files.
Added an update_validation_data.sh script that calls the
update_gadm_data.sh, update_geonames_data.sh, and geonames-to-gadm SQL
scripts.