Add latency option.

Aliased to -l.

middleman-core/lib/middleman-core/cli/server.rb

@@ -45,6 +45,11 @@ module Middleman::Cli
       :type    => :boolean,
       :default => false,
       :desc    => 'Force file watcher into polling mode'
+    method_option :latency,
+      :type    => :string,
+      :aliases => "-l",
+      :default => "0.25",
+      :desc    => 'Set file watcher latency, in seconds'
 
     # Start the server
     def server
@@ -67,6 +72,7 @@ module Middleman::Cli
         :disable_watcher   => options["disable_watcher"],
         :reload_paths      => options["reload_paths"],
         :force_polling     => options["force_polling"]
+        :latency           => options["latency"]
       }
 
       puts "== The Middleman is loading"