Add actions to moderation menu

Closes #4 (closed)

This MR depends on !6 (merged)

src/api/__mocks__/users.js

@@ -27,3 +27,15 @@ export async function searchUsers(query, showLocalUsersOnly, token, page = 1) {
     page_size: 50
   }})
 }
+
+export async function addRight(nickname, right, token) {
+  return Promise.resolve({ data:
+    { [`is_${right}`]: true }
+  })
+}
+
+export async function deleteRight(nickname, right, token) {
+  return Promise.resolve({ data:
+    { [`is_${right}`]: false }
+  })
+}