Add general proxy support (fixes #259)

Change-Id: I63a3eb1e14a35067522fa8ee9efc905059dea087
diff --git a/kalamar.conf b/kalamar.conf
index f5bed8e..e3aa00b 100644
--- a/kalamar.conf
+++ b/kalamar.conf
@@ -71,6 +71,12 @@
     #   items_per_page => 20,
     #   context => '20-t,20-t',
     #   alignment => 'left' # or 'right' or 'center'
-    # }
+    # },
+
+    # proxies => [{
+    #   root_path => '/plugin/export',
+    #   mount => 'http://export-plugin:3333',
+    #   service => 'export-plugin-proxy'
+    # }]
   }
 }