Added new setting, widget, form and auth backend to allow login via user email address

To enable:
AUTHENTICATION_BACKENDS = ('common.auth.email_auth_backend.EmailAuthBackend',)
COMMON_LOGIN_METHOD = 'email'

apps/common/forms.py

@@ -2,9 +2,12 @@ from django import forms
 from django.utils.translation import ugettext_lazy as _
 from django.db import models
 from django.contrib.auth.models import User
+from django.contrib.auth.forms import AuthenticationForm
+from django.contrib.auth import authenticate
 
 from common.utils import return_attrib
-from common.widgets import DetailSelectMultiple, PlainWidget, TextAreaDiv
+from common.widgets import DetailSelectMultiple, PlainWidget, \
+    TextAreaDiv, EmailInput
 
 
 class DetailForm(forms.ModelForm):
@@ -115,3 +118,29 @@ class UserForm(forms.ModelForm):
     class Meta:
         model = User
         fields = ('first_name', 'last_name')
+
+
+class EmailAuthenticationForm(AuthenticationForm):
+    """
+    Override the default authentication form to use email address
+    authentication
+    """
+    email = forms.CharField(label=_(u'Email'), max_length=75, 
+        widget=EmailInput()
+    )
+    
+    def clean(self):
+        email = self.cleaned_data.get('email')
+        password = self.cleaned_data.get('password')
+
+        if email and password:
+            self.user_cache = authenticate(email=email, password=password)
+            if self.user_cache is None:
+                raise forms.ValidationError(_('Please enter a correct email and password. Note that the password fields is case-sensitive.'))
+            elif not self.user_cache.is_active:
+                raise forms.ValidationError(_('This account is inactive.'))
+        self.check_for_test_cookie()
+        return self.cleaned_data
+
+# Remove the inherited username field 
+EmailAuthenticationForm.base_fields.keyOrder = ['email', 'password']