Cleanup log messaging

This change corrects a few logging issues:

 * Standardized formatting errors with '%v'.
 * Standardized failure warning word usage.
 * Corrected an instance of using the standard log library when
   the gitea log library should be used instead.

main.go

@@ -38,7 +38,7 @@ func main() {
 	app.Flags = append(app.Flags, []cli.Flag{}...)
 	err := app.Run(os.Args)
 	if err != nil {
-		log.Fatal(4, "Fail to run app with %s: %v", os.Args, err)
+		log.Fatal(4, "Failed to run app with %s: %v", os.Args, err)
 	}
 
 }