Workout templates

[rsepassi]

We need a progression of workouts that are composed of 5 sets each. We should be able to know which workout a user is currently on, what's next, etc.

It'd also be great to know if a user wasn't able to complete the workout (i.e. clicked "Done with workout" before they were down to 0) so that we could have the user do that workout again.

I'm not sure that the current workouts table is sufficient.

First thought is to add a column to users called current_workout_id and another column to workouts called template_workout_id that points to the workout that it's a part of.