Provide an implementation for silence_stream inside webrat.

I added the implementation to webrat/core/configuration.rb because
it seems to me that this always gets read first. I decided to put
it inside a util module Webrat::SilentStream and include this where
appropriate, instead of altering Kernel.

lib/webrat/core/configuration.rb

@@ -2,6 +2,17 @@ require "webrat/core_extensions/deprecate"
 
 module Webrat
   
+  module SilentStream
+    def silence_stream(stream)
+      old_stream = stream.dup
+      stream.reopen(RUBY_PLATFORM =~ /mswin/ ? 'NUL:' : '/dev/null')
+      stream.sync = true
+      yield
+    ensure
+      stream.reopen(old_stream)
+    end
+  end
+
   # Configures Webrat. If this is not done, Webrat will be created
   # with all of the default settings.
   def self.configure(configuration = Webrat.configuration)

lib/webrat/selenium/application_server.rb

@@ -3,6 +3,8 @@ module Webrat
 
     class ApplicationServer
       
+      include Webrat::SilentStream
+
       def self.boot
         case Webrat.configuration.application_framework
         when :sinatra

lib/webrat/selenium/selenium_rc_server.rb

@@ -3,6 +3,8 @@ module Webrat
 
     class SeleniumRCServer
       
+      include Webrat::SilentStream
+
       def self.boot
         new.boot
       end

lib/webrat/selenium/selenium_session.rb

@@ -22,6 +22,7 @@ module Webrat
 
   class SeleniumSession
     include Webrat::SaveAndOpenPage
+    include Webrat::SilentStream
 
     def initialize(*args) # :nodoc:
     end
@@ -182,15 +183,6 @@ module Webrat
 
   protected
 
-    def silence_stream(stream)
-      old_stream = stream.dup
-      stream.reopen(RUBY_PLATFORM =~ /mswin/ ? 'NUL:' : '/dev/null')
-      stream.sync = true
-      yield
-    ensure
-      stream.reopen(old_stream)
-    end
-
     def setup #:nodoc:
       Webrat::Selenium::SeleniumRCServer.boot
       Webrat::Selenium::ApplicationServer.boot