enable impersonation for creating and updating revisions

Summary: moved the ---act-as-user flag into the same section as user and cert.  Then updated Conduit constructors as necessary.

Test Plan:
created and updated
https://test.phab.dev.bloomberg.com/D367 via the phabberwocky user/cert impersonated as me

Reviewers: jevripio

Reviewed By: jevripio

CC: arcyd

Differential Revision: https://all.phab.dev.bloomberg.com/D52145