async ensureStarted(options) {
        const portPolling = require('./utils/port-polling');
        const semver = require('semver');

        options = Object.assign({
            stopOnError: true,
            port: this.instance.config.get('server.port'),
            host: this.instance.config.get('server.host', 'localhost'),
            useNetServer: semver.major(this.instance.version) >= 2,
            useV4Boot: semver.major(this.instance.version) >= 4
        }, options || {});

        try {
            await portPolling(this.ui, options);
        } catch (error) {
            if (options.stopOnError) {
                try {
                    await this.stop();
                } catch (e) {
                    // ignore stop error
                }
            }

            throw error;
        }
    }
General implementation of figuring out if the Ghost blog has started successfully.

@returns {Promise<any>}