Remove custom email widget and use Django's

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/authentication/forms.py

@@ -5,10 +5,9 @@ import warnings
 from django import forms
 from django.contrib.auth import authenticate
 from django.contrib.auth.forms import AuthenticationForm
+from django.forms.widgets import EmailInput
 from django.utils.translation import ugettext_lazy as _
 
-from mayan.apps.common.widgets import EmailInput
-
 
 class EmailAuthenticationForm(forms.Form):
     """