issue 222 - redshift config params are not being sent to open_psql_shell

[p5k6]

comes up when using dataduct sql_shell redshift. Error message (currently) is

TypeError: open_psql_shell() takes exactly 1 argument (0 given)

added the redshift configs. All tests pass locally. Did not add a test for this directly as I could not find any tests for this particular module.

Additionally, I opened the PR against develop, as it appears to be more up to date than master. If I need to switch it to master let me know!

[p5k6]

Link to issue: https://github.com/coursera/dataduct/issues/222

[p5k6]

Rebased to latest build so that tests would pass :smile:

[cliu587]

LGTM. Thanks!