Restore Django 1.6- tests, though this begs for deprecation now..

fluent_contents/forms/widgets.py

@@ -2,12 +2,16 @@
 from django.forms.widgets import Widget
 from django.template.loader import render_to_string
 from django.utils.safestring import mark_safe
-from django.forms.utils import flatatt
 from django.utils.html import escape
 from fluent_contents.models import get_parent_language_code
 from fluent_contents.models.managers import get_parent_active_language_choices
 from fluent_utils.django_compat import smart_text
 
+try:
+    from django.forms.utils import flatatt  # Django 1.7+
+except ImportError:
+    from django.forms.util import flatatt  # Django 1.6-
+
 
 class PlaceholderFieldWidget(Widget):
     """