refs #9865
- removed all `oauth2` and token-based ESA auth
- added new `cookie` authenticator which handles session creation
- updated the session store to extend from the `ephemeral` in-memory store and to restore by fetching the currently logged in user and using the success/failure state to indicate authentication state
- ESA automatically calls this `.restore()` method on app boot
- the `session` service caches the current-user query so there's no unnecessary requests being made for the "logged in" state
- removed the now-unnecessary token refresh and logout routines from the `application` route
- removed the now-unnecessary token refresh routines from the `ajax` service
- removed `access_token` query param from iframe file downloaders
- changed Ember Data adapters and `ghost-paths` to use the `/ghost/api/v2/admin/` namespace
no issue
- switch `jscs` and `jshint` inline config to `eslint` config
- fix eslint errors, predominantly in tests where the config now the main app config more closely
no issue
- updates `package.json` details to better reflect the separation from the `Ghost` package
- update ember config and all import statements to reflect the new `ghost-admin` module name in `package.json`
