Limit sqlite to one connection

we use the database connection inside the handlers from the http
framework, therefore concurrent access occurs. Sqlite cannot handle
concurrent writes, so we limit sqlite to one connection.
see https://github.com/mattn/go-sqlite3/issues/274

database/database.go

@@ -15,6 +15,13 @@ func New(dialect, connection, defaultUser, defaultPass string) (*GormDatabase, e
 	if err != nil {
 		return nil, err
 	}
+	// we use the database connection inside the handlers from the http
+	// framework, therefore concurrent access occurs. Sqlite cannot handle
+	// concurrent writes, so we limit sqlite to one connection.
+	// see https://github.com/mattn/go-sqlite3/issues/274
+	if dialect == "sqlite3" {
+		db.DB().SetMaxOpenConns(1)
+	}
 	if !db.HasTable(new(model.User)) && !db.HasTable(new(model.Message)) &&
 		!db.HasTable(new(model.Client)) && !db.HasTable(new(model.Application)) {
 		db.AutoMigrate(new(model.User), new(model.Application), new(model.Message), new(model.Client))