Fixes#4686
Adds tests for @zeit/next-typescript so that we don't regress on this again.
I've fixed an issue in the `next` CLI too which caused lingering processes when the process gets force killed, which is what we do in the test suite, so it kept running if there was no manual quit.
* Use next.config.js instead of package.json
* Remove irrelevant comment
* Integrate with custom webpack config
* Include hotReload option
* Remove async/await for getConfig
* Read package.json, show warning when webpack in config is defined
* Prepend warning message with WARNING
* Update log statements
* Documentation
* Restart server on change of config
* Fix process handling and cases where there is no config
* Also restart server when config file gets deleted
* Changed second parameter of webpack to config
* Support for returning Promise
* Update documentation, fix bug with webpack config
* Remove package.json, cdn and hotReload from config
* Added next bootstrap command for starting a new project
* renamed bootstrap to init and check we are not in a dir called pages
* Removed extra empty line