Support non-local database

[karlcz]

• Make sure the database connection string in hatrac_config.json is really honored and can connect to a remote postgres database cluster
• Make sure the ermrest-deploy process honors the configured database connection string for non-local deployment.
• Allow renaming of the hatrac database so multiple hatrac deployments can share one database cluster without interference
• Allow renaming of the hatrac database role so that multiple deployments in one cluster have privilege isolation