[#7] Check empty line after commit's header

Signed-off-by: Ekaterina Lebedeva <ekaterina.lebedeva@yadro.com>

main.go

@@ -77,6 +77,13 @@ func main() {
 			return nil
 		}
 
+		// Check empty line after header.
+		if 1 < len(lines) && lines[1] != "" {
+			fail = true
+			fmt.Printf("Error: second line must be empty '%s' [%s]\n", lines[1], id)
+			return nil
+		}
+
 		// Check commit sign-off.
 		if !rxSignOff.MatchString(lines[len(lines)-1]) {
 			fail = true