Check whether rpm is installed (fanal#39)

* Check whether rpm is installed

* Apply the review

utils/utils.go

@@ -3,6 +3,7 @@ package utils
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 )
 
@@ -29,3 +30,10 @@ func StringInSlice(a string, list []string) bool {
 	}
 	return false
 }
+
+func IsCommandAvailable(name string) bool {
+	if _, err := exec.LookPath(name); err != nil {
+		return false
+	}
+	return true
+}