Change primary key fields to be auto-incrementing

This is primarily for testing purposes since the staging data will
already contain primary keys and the warehouse is managed externally.

Signed-off-by: Byron Ruth <b@devel.io>
Implement limited set of OMOP model processors

This is a very basic implementation and does not include any
optimizations such as caching or parallelization.

Signed-off-by: Byron Ruth <b@devel.io>