BUG-670: enable reporting of PCEP errors

Adds a place where errors reported by a PCC can be stored and fills it
when a PCUpd request results in a failure.

Change-Id: Id235effcf6069b66b9f3f3cae19d0cb495ee332f
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-670: enable reporting of PCEP errors"