package schema for backup/restore

Backup/Restore need to be able to drop the current database and then create a database of any version for importing old data.

The process is dropDb(), createTables(int version), (insert data), addConstraints(), update().

To do this we will ship and store schema creation scripts for each type of database supported. The scripts will be broken into:-

• dbname-tables-version.sql
• dbname-constraints-version.sql
• dbname-drop-version.sql

the dbspecific scripts will be stored in a separate directory, currently hsql, mysql, postgresql.
(not part of this jira) upgrade scripts will be stored in separate db specific directories too.