Give kimchi a specific pam service

--- a/src/kimchi/auth.py
+++ b/src/kimchi/auth.py
@@ -141,7 +141,7 @@
         return self.user
 
     @staticmethod
-    def authenticate(username, password, service="passwd"):
+    def authenticate(username, password, service="kimchi"):
         '''Returns True if authenticate is OK via PAM.'''
         def _auth(result):
             def _pam_conv(auth, query_list, userData=None):
