Improve automatic emails with temporary urls

This MR targets the improvement for automatic emails concerning validation of new users by supervisors/re-validation of users.

Fixes #542 (closed)

Fixes #550 (closed)

beat/web/accounts/migrations/0012_accounts_temporary_url.py

 # -*- coding: utf-8 -*-
-# Generated by Django 1.11.26 on 2020-04-27 23:41
+# Generated by Django 1.11.26 on 2020-05-02 03:02
 from __future__ import unicode_literals
 
 from django.db import migrations, models
@@ -17,7 +17,7 @@ class Migration(migrations.Migration):
             name='TemporaryUrl',
             fields=[
                 ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('status', models.CharField(choices=[('V', 'Supervisor validates supervisee'), ('Y', 'Self yearly revalidation from sueprvisee')], default='V', max_length=1)),
+                ('status', models.CharField(choices=[('V', 'Supervisor validates supervisee'), ('Y', 'Self yearly revalidation from supervisee')], default='V', max_length=1)),
                 ('url_hash', models.CharField(max_length=32, unique=True, verbose_name='Url')),
                 ('expires', models.DateTimeField(verbose_name='Expires')),
                 ('supervision_track', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='supervisees', to='accounts.SupervisionTrack')),