Add user-configurable option to suppress git, mercurial, and perforce warnings.

Review Request #8638 — Created Jan. 20, 2017 and submitted — Latest diff uploaded




Prior to this change, it was not possible for the user to suppress warnings from git, mercurial, and perforce. This could result in a large number of warning messages output to the log which can be cumbersome and fill up the console window.

This change allows the user to suppress warnings from rbtools/clients/, rbtools/clients/, and rbtools/clients/ by setting SUPPRESS_CLIENT_WARNINGS in .reviewboardrc to True.

Checked that the warning message in is suppressed when the SUPPRESS_CLIENT_WARNINGS is set to True.