minor adjustments
add group head to groups module
add form validation on users grid & align labels
add backbone validation on POST
implement classes module
fix filling form
add teachers_subjects controller
implement add form on classes Grid
realise POST on classes grid
fix unique validation
fix post
implement edit form
implement PUT on classes grid
add localisation for classes module
add teachers module & make changes bbGrid library
fixing add/edit forms
fixing GRID
implement teachers module
add students GRID
implemet add func