Add watcher routes to backend and frontend; implement routing and UI components for watcher management

backend/src/models/index.js

@@ -16,6 +16,7 @@ const SickType = require('./SickType');
 const Timefix = require('./Timefix');
 const Timewish = require('./Timewish');
 const Invitation = require('./Invitation');
+const Watcher = require('./Watcher');
 
 module.exports = {
   User,
@@ -30,6 +31,7 @@ module.exports = {
   SickType,
   Timefix,
   Timewish,
-  Invitation
+  Invitation,
+  Watcher
 };