Implement functionality to assigne Licenses to Packages and show existing Licenses (#17)

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#17

epdb/models.py

@@ -204,9 +204,14 @@ class ScenarioMixin(models.Model):
     class Meta:
         abstract = True
 
+class License(models.Model):
+    link = models.URLField(blank=False, null=False, verbose_name='link')
+    image_link = models.URLField(blank=False, null=False, verbose_name='Image link')
+
 
 class Package(EnviPathModel):
     reviewed = models.BooleanField(verbose_name='Reviewstatus', default=False)
+    license = models.ForeignKey('epdb.License', on_delete=models.SET_NULL, blank=True, null=True, verbose_name='License')
 
     def __str__(self):
         return f"{self.name} (pk={self.pk})"