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 2020-05-02 03:02
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("accounts", "0011_check_all_accounts"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            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 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",
+                    ),
+                ),
+            ],
+        ),
+        migrations.AlterField(
+            model_name="profile",
+            name="status",
+            field=models.CharField(
+                choices=[
+                    ("N", "New User"),
+                    ("W", "Waiting Validation"),
+                    ("A", "Accepted"),
+                    ("R", "Rejected"),
+                    ("Y", "Yearly revalidation"),
+                    ("B", "Blocked no supervisor"),
+                ],
+                default="B",
+                max_length=1,
+            ),
+        ),
+    ]