async getAvailableConfigs() {
        const configRegex = /^config\.([a-z]+)\.json$/;
        const files = await fs.readdir(this.dir);

        return files.reduce((configs, f) => {
            const matches = f.match(configRegex);
            if (!matches) {
                return configs;
            }

            return {
                ...configs,
                [matches[1]]: new Config(path.join(this.dir, f))
            };
        }, {});
    }
Gets a list of availble configurations for this instance

@method getAvailableConfigs
@return {Promise<{[s: string]: Config}>}