add email feature

apps/activity/forms.py

@@ -120,3 +120,12 @@ class GuestForm(forms.ModelForm):
                 },
             ),
         }
+
+
+class EmailForm(forms.Form):
+    """
+    Form to export guest list by email
+    """
+    emails = forms.CharField()
+    emails.label = _("Emails")
+    emails.widget.attrs['placeholder'] = _("Emails, separated by a comma")