Fix the zuul_enqueue tool

The author name on a comment is different to the username of the
system leaving the vote. Allow this to be configured.

Change-Id: I3e2da5eba287c1609df9cca0617fca770a9fb2a9
diff --git a/tools/zuul_enqueue.py b/tools/zuul_enqueue.py
index 2b31567..0073257 100755
--- a/tools/zuul_enqueue.py
+++ b/tools/zuul_enqueue.py
@@ -8,6 +8,7 @@
 
 # Set the user to watch
 user = 'turbo-hipster'
+author_name = 'DB Datasets CI'
 
 # Grab a list of missing or negative reviews for a user:
 url = ("https://review.openstack.org/changes/?q=status:open "
@@ -33,7 +34,7 @@
             if message['_revision_number'] < patchset:
                 # Finished looking at all the messages on this patchset
                 break
-            if message['author']['name'] == user:
+            if message['author']['name'] == author_name:
                 last_message = message['message']
                 break