Fix promise chaining when loading serviceuser details screen

Sometimes generating a HTTP password could seem to be stuck. In such
cases the request was never sent because the pluginRestApi object was
null. This happened, because the relevant permission check was done
too late due to improper promise chaining.

Change-Id: I620525f520c62271cfc2009c477d8f2f07ade75a

web/gr-serviceuser-detail.ts

diff --git a/web/gr-serviceuser-detail.ts b/web/gr-serviceuser-detail.ts
index 10decf2..e2d4f94 100644
--- a/web/gr-serviceuser-detail.ts
+++ b/web/gr-serviceuser-detail.ts
@@ -372,18 +372,18 @@
   }
 
   private getPluginConfig() {
-    return Promise.resolve(this.getPermissions()).then(() => {
-      this.pluginRestApi
-        .get<ConfigInfo>('/config/server/serviceuser~config/')
-        .then(config => {
-          if (!config) {
-            return;
-          }
-          this.emailAllowed = config.allow_email || this.isAdmin;
-          this.ownerAllowed = config.allow_owner || this.isAdmin;
-          this.httpPasswordAllowed = config.allow_http_password || this.isAdmin;
-        });
-    });
+    return this.getPermissions()
+      .then(() =>
+        this.pluginRestApi.get<ConfigInfo>('/config/server/serviceuser~config/')
+      )
+      .then(config => {
+        if (!config) {
+          return;
+        }
+        this.emailAllowed = config.allow_email || this.isAdmin;
+        this.ownerAllowed = config.allow_owner || this.isAdmin;
+        this.httpPasswordAllowed = config.allow_http_password || this.isAdmin;
+      });
   }
 
   private getServiceUser() {