BUG-374: cleanup error messages present in controller startup

This tones down the "BUG" word which may alarm a casual user. These
still indicate run-time problems which should not occur in a
deterministic run-time environment.

Change-Id: I80871ea1999d2a92d6b343d83ddfc784e7e29ecc
Signed-off-by: SahilShah <sahil4.s@tcs.com>
Signed-off-by: Robert Varga <rovarga@cisco.com>
(cherry picked from commit 75c047e77f3f0db01af242d16f79d7a73266d435)
Merge "BUG-374: cleanup error messages present in controller startup" into stable/hydrogen