Rename zuul-server zuul-scheduler

This is what we call it.

Change-Id: If4ae79eddff9151979271ae7faf4348014528e46
diff --git a/setup.cfg b/setup.cfg
index 7ddeb84..bd76d8b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -21,7 +21,7 @@
 
 [entry_points]
 console_scripts =
-    zuul-server = zuul.cmd.server:main
+    zuul-scheduler = zuul.cmd.scheduler:main
     zuul-merger = zuul.cmd.merger:main
     zuul = zuul.cmd.client:main
     zuul-cloner = zuul.cmd.cloner:main