'admin' tool should use pq

[ocket8888]

I'm submitting a ...

• improvement request (usability, performance, tech debt, etc.)

Traffic Control components affected ...

• other

Current behavior:

admin shells out to subprocess using a psql binary` for database operations.

Expected / new behavior:

The admin tool should use a postgresql adapter to make database connections instead of relying on shelling out to a psql binary somewhere in the system's path. That'd make database errors more transparent (I'm currently getting the extremely helpful error message "unable to determine if user already exists: exit status 2"), and would eliminate the dependency on the postgresql client.

[MylesBock]

I think I have something that could end up solving this, may I be assigned this issue?