fix incorrect name in middleware

Author: Austin Morton

setup.py

@@ -5,7 +5,7 @@
 README = open(os.path.join(here, 'README.md')).read()
 
 
-version = '0.1.0'
+version = '0.1.1'
 
 install_requires = [
     'django-auth-ldap',

src/django_remote_auth_ldap/middleware.py

@@ -4,5 +4,5 @@
 
 class RemoteUserMiddleware(middleware.RemoteUserMiddleware):
     @property
-    def HEADER(self):
+    def header(self):
         return settings.HEADER