engine : Support logging of commands parameters

When debug mode is enabled the command parameters
excluding the ones in the VdcParametersBase are
logged when the command is executed.

Fields that need to excluded from the debug log
like passwords can be marked with the new Annotation
ShouldNotBeLogged and they will be skipped from the log

Change-Id: Idfd9423e92f9f9c9a51eca24b20157cc32681018
Bug-Url: https://bugzilla.redhat.com/1095240
Signed-off-by: Ravi Nori <rnori@redhat.com>