Added database schema dump file pg-pin-schema.sql

This will enable tracking of changes to the database schema.
The command to generate this file is:
pg_dump -s -f pg-pin-schema.sql -U <dbuser> pin

* Please generate this file from your local database after you make
  any change to the structure which is required for your code to
  work.
Merge pull request #6 from mach24/live

Added database schema dump file pg-pin-schema.sql