getInstance(name) {
        if (!name) {
            return this.cachedInstance(process.cwd());
        }

        const instance = this.globalConfig.get(`instances.${name}`);
        if (!instance) {
            return null;
        }

        return this.cachedInstance(instance.cwd);
    }
Returns an instance by name, or the instance of the current
working directory

@param {string} Optional name of instance to retrieve
@return {Instance}
@method getInstance
@public