Added assistant column to class list
Removed trash button on class list for course's default class
class edit: when a class has no students, show a message
Fixed no students found pt_BR message
Merge branch '3793-cria-coluna-professor' into 3639-ajustes-gestao-turma

Conflicts:
	locale/es/LC_MESSAGES/django.po
	locale/it/LC_MESSAGES/django.po
	locale/pt_BR/LC_MESSAGES/django.po
	themes/default/templates/classes.html
Merge branch '3639-ajustes-gestao-turma'