added email field validation

evapp/models.py

@@ -47,7 +47,7 @@ class Employee(models.Model):
     firstname = models.CharField(max_length=50, verbose_name="Vorname")
     lastname = models.CharField(max_length=50, verbose_name="Nachname")
     intern = models.BooleanField(verbose_name='Interne_r Mitarbeiter_in?', default=True)
-    email = models.CharField(max_length=50, verbose_name="E-Mail-Adresse")
+    email = models.EmailField(max_length=50, verbose_name="E-Mail-Adresse")
     department = models.CharField(max_length=5, choices=DEPARTMENT_CHOICES.items())
     team = models.CharField(max_length=20, null=True, blank=True) # TODO? besser als choices?