Merge main and common apps, extract authentication functionality to new authentication app. Closes issues #179 and #180

mayan/apps/authentication/auth/email_auth_backend.py

@@ -0,0 +1,22 @@
+from django.contrib.auth import get_user_model
+from django.contrib.auth.backends import ModelBackend
+
+
+class EmailAuthBackend(ModelBackend):
+    """
+    Email Authentication Backend
+
+    Allows a user to sign in using an email/password pair rather than
+    a username/password pair.
+    """
+
+    def authenticate(self, email=None, password=None):
+        UserModel = get_user_model()
+        try:
+            user = UserModel.objects.get(email=email)
+            if user.check_password(password):
+                return user
+        except UserModel.DoesNotExist:
+            # Run the default password hasher once to reduce the timing
+            # difference between an existing and a non-existing user (#20760).
+            UserModel().set_password(password)