Move login to oauth.

This unifies Mastodon and Pleroma logins and makes it easier to implement SSO schemes.

src/components/registration/registration.js

+import oauthApi from '../../services/new_api/oauth.js'
+
 const registration = {
   data: () => ({
     user: {},
@@ -25,9 +27,23 @@ const registration = {
       this.$store.state.api.backendInteractor.register(this.user).then(
         (response) => {
           if (response.ok) {
-            this.$store.dispatch('loginUser', this.user)
-            this.$router.push('/main/all')
-            this.registering = false
+            const data = {
+              oauth: this.$store.state.oauth,
+              instance: this.$store.state.instance.server
+            }
+            oauthApi.getOrCreateApp(data).then((app) => {
+              oauthApi.getTokenWithCredentials(
+                {
+                  app,
+                  instance: data.instance,
+                  username: this.user.username,
+                  password: this.user.password})
+                .then((result) => {
+                  this.$store.commit('setToken', result.access_token)
+                  this.$store.dispatch('loginUser', result.access_token)
+                  this.$router.push('/main/friends')
+                })
+            })
           } else {
             this.registering = false
             response.json().then((data) => {