Merge branch 'topic/school' into topic/teacher
Merge branch 'topic/invite' into topic/teacher

Conflicts:
	src/Due/EksamensBundle/Resources/config/services.yml
Merge branch 'topic/admin' into topic/teacher

Conflicts:
	composer.lock
	src/Due/EksamensBundle/Resources/config/services.yml
Created an action for inviting a teacher to the school.
Configured invitation form of teachers to be accessible only by the admins of a current school.
Merge branch 'topic/admin' into topic/teacher
Fixed ManyToOne connection on Teacher entity.
Created migration for ManyToOne connections on Teacher entity.
Unique user as teacher per school.
Added teacher invitation samples to fixture of Teacher.