support heroku deploy

[c9s]

Button: https://devcenter.heroku.com/articles/heroku-button

App json: https://devcenter.heroku.com/articles/app-json-schema

Reference: https://devcenter.heroku.com/articles/getting-started-with-go?singlepage=true#define-a-procfile

Notice:

• MySQL is not natively supported, you need to install a plugin.
• We need to run migration script

[c9s]

Need to find out the way for user to custom the config file.