1. register base bindings.
2. register base service providers(\Illuminate\Events\EventServiceProvider and \Illuminate\Routing\RoutingServiceProvider).
3. register core service aliases
(‘app’, ‘auth’, ‘auth.driver’, ‘blade.compiler’, ‘cache’, ‘cache.store’, ‘config’, ‘cookie’, ‘encrypter’, ‘db’, ‘db.connection’,
‘events’, ‘files’, ‘filesystem’, ‘filesystem.disk’, ‘filesystem.cloud’, ‘hash’, ‘translator’, ‘log’, ‘mailer’,
‘auth.password’, ‘auth.password.broker’, ‘queue’, ‘queue.connection’, ‘queue.failer’, ‘redirect’, ‘redis’, ‘request’,
‘router’, ‘session’, ‘session.store’, ‘url’, ‘validator’, ‘view’), and these core service will be registered later.
4. set the base path, including
‘path’ = __DIR__ . ‘/app’, ‘path.base’ = __DIR__ , ‘path.lang’ = __DIR__ . ‘/resources/lang’,
‘path.config’ = __DIR__ . ‘/config’, ‘path.public’ = __DIR__ . ‘/public’, ‘path.storage’ = __DIR__ . ‘/storage’,
‘path.database’ = __DIR__ . ‘/database’, ‘path.resources’ = __DIR__ . ‘/resources’,
‘path.bootstrap’ = __DIR__ . ‘/bootstrap’. U can get theses path everywhere in the way,
e.g. public_path(‘/js/app.js’) === __DIR__ . ‘/public/js/app.js’;
参考文章：https://segmentfault.com/a/1190000006909579
