use more compatible url import

defaults module is deprecated in later Django's

django_sshkey/urls.py

@@ -15,7 +15,10 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with django-sshkey.  If not, see <http://www.gnu.org/licenses/>.
 
-from django.conf.urls.defaults import patterns, url
+try:
+  from django.conf.urls.defaults import patterns, url
+except ImportError:
+  from django.conf.urls import patterns, url
 
 urlpatterns = patterns('django_sshkey.views',
   url(r'^lookup$', 'lookup'),