Send error messages about incompatible bridge settings to stderr
Send error messages about incompatible bridge settings to stderr

n054/weave,weaveworks/weave,n054/weave,n054/weave,paulbellamy/weave,weaveworks/weave,weaveworks/weave,paulbellamy/weave,paulbellamy/weave,n054/weave,n054/weave,weaveworks/weave,paulbellamy/weave