Add scripts for manipulating databases
In this change, we have add two batch scripts to allow users to init/reinit databases.
init-postgres.sh: The script to run with an empty database.
reinit-postgres.sh: The script to run to refresh our database into a complete new environment.

create_database.sql: Used to initialize database.
drop_create_database.sql: Used to reinitialize database.
schema.sql: Database schemas.