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