Adding scripts for running examples on each database.

mysql/_example/test.sh

+cat example.sql | mysql -uupperio -pupperio upperio_tests
+go run main.go

postgresql/_example/test.sh

+#!/bin/sh
+cat example.sql | PGPASSWORD=upperio psql -Uupperio upperio_tests
+go run main.go

sqlite/_example/test.sh

+#!/bin/sh
+rm -f example.db
+cat example.sql | sqlite3 example.db
+go run main.go