Add WIP workout tab
WIP template for workouts - need to split this
Refactor workout templating into separate functions
Add database schema, query functions and REST interface for workouts
Make 'Add Set' button work

Add server-side handling of adding new exercise sets.

Implement client-side logic to actually do something when pressing the
"Add Set" button.
Add features to add workouts and exercises

- Add 'new workout' button
- Add UI & server-side for adding new exercises into workouts
- Prettify and make layout more mobile friendly
Show Workout tab link in the top navbar
Add UI to add new types of exercises
Add server-side support for exercise types

Add "body weight" and "always weighted" types for exercises.
Add UI for setting exercise type to weighted or bodyweight

- plus some REST interface changes
- plus some clean up