metrics.go
func (m *CirconusMetrics) SetMetricTags(name string, tags []string) bool {
	return m.check.AddMetricTags(name, tags, false)
}
func (m *CirconusMetrics) SetMetricTags(name string, tags []string) bool {
	return m.check.AddMetricTags(name, tags, false)
}
// SetMetricTags sets the tags for the named metric and flags a check update is needed