[dagster-postgres] update config to Selector

Authored by alangenfeld on Jan 13 2020, 6:33 PM.


[dagster-postgres] update config to Selector

Summary: This allows moving connection string contruction to code for things like our helm charts and allows us to url quote passwords that may contain characters that need to be escaped

Test Plan: added test cases

Reviewers: max, schrockn

Reviewed By: schrockn

Differential Revision: https://dagster.phacility.com/D1830