Add gearman server port configuration

This change adds the port configuration option to set a custom port
for the gearman server.

Change-Id: I1b65f93fa0403ff10e00a97afcdb4a3b512eb372
diff --git a/doc/source/admin/components.rst b/doc/source/admin/components.rst
index 2c70d47..fbb8cbc 100644
--- a/doc/source/admin/components.rst
+++ b/doc/source/admin/components.rst
@@ -149,6 +149,11 @@
 
       IP address or domain name on which to listen.
 
+   .. attr:: port
+      :default: 4730
+
+      TCP port on which to listen.
+
    .. attr:: log_config
 
       Path to log config file for internal Gearman server.