Added functionality to generate a DDL for a Datastore.
Updated Datastore.create to use DDL and allocate table references at the end (for foreign keys).
Added BigDecimal -> DECIMAL support in table creation.
Added ORMTable persisting, inserting, and updating to allow extension modification of instances before they are persisted.
Created ModifiedSupport trait to mix into ORMTables with a field "modified" to make sure the modified is always updated upon persist.