Postgres Backend for Red October

When running several Red October instances that use the same set of accounts, the disk vault can easily get out of sync. It would be useful to have a database backend, preferably PostgreSQL.

• define the schema
• create a tool to migrate a disk vault into the postgres database
• create a common interface for all operations that would use the disk vault
• implement a postgres backend for the disk vault
• add a flag to use the postgres backend