Updated edx-auth-backends and removed pinned version of python-social-auth

requirements/base.txt

@@ -10,7 +10,7 @@ djangorestframework==3.3.3
 djangorestframework-jwt==1.7.2
 django-rest-swagger[reST]==0.3.5
 dry-rest-permissions==0.1.6
-edx-auth-backends==0.2.1
+edx-auth-backends==0.2.3
 edx-ccx-keys==0.2.0
 edx-drf-extensions==0.5.0
 edx-opaque-keys==0.3.0
@@ -19,5 +19,4 @@ elasticsearch>=1.0.0,<2.0.0
 html2text==2016.4.2
 pycountry==1.20
 python-dateutil==2.5.2
-python-social-auth==0.2.14
 pytz==2015.7