Add planned workout

backend/secfit/requirements.txt

backend/secfit/workouts/admin.py

backend/secfit/workouts/migrations/0004_workout_planned.py

backend/secfit/workouts/models.py

backend/secfit/workouts/serializers.py

backend/secfit/workouts/views.py

frontend/www/plannedWorkout.html

frontend/www/scripts/plannedWorkout.js

frontend/www/scripts/workout.js

frontend/www/scripts/workouts.js

frontend/www/workout.html

frontend/www/workouts.html