Improve the language configuration overview
Fix unitialised variables
Correctly filter exercises by language on muscle overview
Add submit text to form to copy workout
Add localization files for JQuery's datepicker
Add first version of Spanish translation
Add fixtures with language configuration for Spanish
Fix broken HTML
Fix issue with sorting

When a day had more than one days of the week, the day would be rendered
more than once in the overview. With this, the training days are ordered
by the ID of the first week day.
More elegant empty query for workout logs
Update D3 and JQuery to latest versions
Animate the data points in the body weight chart, opening them in succession
Make the animation duration independent of the number of data points
Correctly handle non-ASCII headers for the weight CSV export
Commit missing migration file
Do sanity test when rearranging the order of the sets
Update Bulgarian and Spanish translations
Use a permission mixin to check for permissions in views

This makes sure that for all access to the class the permission is
checked and gets rid of all thos decorators in the urls.py files
Rename mixin to be more consistent with the other generic views
Remove unused imports