Fix webrick when using the debugger (closes #9348) [bronson]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7639 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/lib/commands/servers/webrick.rb

 require 'webrick'
 require 'optparse'
+require 'commands/servers/base'
 
 OPTIONS = {
   :port         => 3000,