Adds edit functionality

This version of the app adds these new features:

• Tasks and task lists can be created, edited, and deleted from within the app.
• The app can fetch multiple pages of tasks or task lists. This is needed when there are more than 20 task lists or more than 100 tasks.

Basic UWP App

• The UWP app works with google login.
• You can view (but not edit) task lists and tasks.
• The other platforms still need to implement the google login.
• The data is always fetched online and there is no local storage.
• The app is not thoroughly tested and doesn't work without an internet connection.