Remove status_url option

It's only used in the start message, so allow start message
customization in the pipeline itself.

This is in service of reducing reporter dependency on scheduler.

Change-Id: I395d277d414ae8a69d6c3f84e5c41a23585c5f28
diff --git a/zuul/configloader.py b/zuul/configloader.py
index 1703b0f..8d92e2b 100644
--- a/zuul/configloader.py
+++ b/zuul/configloader.py
@@ -349,6 +349,8 @@
         pipeline.success_message = conf.get('success-message',
                                             "Build succeeded.")
         pipeline.footer_message = conf.get('footer-message', "")
+        pipeline.start_message = conf.get('start-message',
+                                          "Starting {pipeline.name} jobs.")
         pipeline.dequeue_on_new_patchset = conf.get(
             'dequeue-on-new-patchset', True)
         pipeline.ignore_dependencies = conf.get(
diff --git a/zuul/model.py b/zuul/model.py
index 93fbb31..8d1c0bf 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -75,6 +75,7 @@
         self.merge_failure_message = None
         self.success_message = None
         self.footer_message = None
+        self.start_message = None
         self.dequeue_on_new_patchset = True
         self.ignore_dependencies = False
         self.job_trees = {}  # project -> JobTree
diff --git a/zuul/reporter/__init__.py b/zuul/reporter/__init__.py
index 777b058..7df1775 100644
--- a/zuul/reporter/__init__.py
+++ b/zuul/reporter/__init__.py
@@ -69,10 +69,7 @@
         return ret
 
     def _formatItemReportStart(self, pipeline, item):
-        msg = "Starting %s jobs." % pipeline.name
-        if self.sched.config.has_option('zuul', 'status_url'):
-            msg += "\n" + self.sched.config.get('zuul', 'status_url')
-        return msg
+        return pipeline.start_message.format(pipeline=pipeline)
 
     def _formatItemReportSuccess(self, pipeline, item):
         return (pipeline.success_message + '\n\n' +