Add support for django 1.7

Signed-off-by: Matheus Faria <matheus.sousa.faria@gmail.com>
Singed-off-by: Gustavo Jaruga <darksshades@hotmail.com>

Author: GustJc

conversejs/forms.py

@@ -8,3 +8,4 @@ class XMPPAccountForm(forms.ModelForm):
 
     class Meta:
         model = XMPPAccount
+        exclude = ()

conversejs/models.py

@@ -2,11 +2,11 @@
 from django.db import models
 
 try:
-    from django.contrib.auth import get_user_model
+    from django.conf import settings
 except ImportError:
     from django.contrib.auth.models import User
 else:
-    User = get_user_model()
+    User = settings.AUTH_USER_MODEL
 
 
 class XMPPAccount(models.Model):