Added the practical group to the database model. Also added the many-to-many and one-to-many relationships
Fixed a method used for the one-to-many relation
Added tests for the practicalgroup and his many-to-many and one-to-many relations
Merge pull request #10 from florisverburg/feature_model_practical_group

Feature model practical group
Menu width edited, and some minor design changes
form names edited
Form layout added
Only bootstrap layout used
Error messages in red text
favicon added
Merge pull request #11 from florisverburg/feature_form_design

Feature form design