Replace fmt.Sprintf with strconv.FormatBool (#24)

This is both faster and simpler.

Author: Bjørn

main.go

@@ -233,7 +233,7 @@ func register(results []gaugeResult) {
 	vulnerabilityGauge.Reset()
 	for _, r := range results {
 		for _, result := range r.results {
-			vulnerabilityGauge.WithLabelValues(r.organization, r.project, result.title, result.severity, boolStr(result.ignored), boolStr(result.upgradeable), boolStr(result.patchable)).Set(float64(result.count))
+			vulnerabilityGauge.WithLabelValues(r.organization, r.project, result.title, result.severity, strconv.FormatBool(result.ignored), strconv.FormatBool(result.upgradeable), strconv.FormatBool(result.patchable)).Set(float64(result.count))
 		}
 	}
 }
@@ -270,10 +270,6 @@ func collect(client *client, organization org) ([]gaugeResult, error) {
 	return gaugeResults, nil
 }
 
-func boolStr(b bool) string {
-	return fmt.Sprintf("%t", b)
-}
-
 type aggregateResult struct {
 	title       string
 	severity    string