adds "exclude" knob in configuration (#505)

lint/config.go

@@ -29,4 +29,5 @@ type Config struct {
 	ErrorCode             int              `toml:"errorCode"`
 	WarningCode           int              `toml:"warningCode"`
 	Directives            DirectivesConfig `toml:"directive"`
+	Exclude               []string         `toml:"exclude"`
 }

main.go

@@ -29,6 +29,11 @@ func main() {
 	if err != nil {
 		fail(err.Error())
 	}
+
+	if len(excludePaths) == 0 { // if no excludes were set in the command line
+		excludePaths = conf.Exclude // use those from the configuration
+	}
+
 	packages, err := getPackages(excludePaths)
 	if err != nil {
 		fail(err.Error())