add port option to ssh config

lib/vagrant/config/ssh.rb

@@ -12,9 +12,11 @@ module Vagrant
       attr_accessor :forward_agent
       attr_accessor :forward_x11
       attr_accessor :sudo_shell
+      attr_accessor :port
 
       def initialize
         @sudo_shell = "bash"
+        @port = nil
       end
 
       def private_key_path

lib/vagrant/ssh.rb

@@ -154,6 +154,9 @@ module Vagrant
       pnum = opts[:port]
       return pnum if pnum
 
+      # Check if a port was specified in the config
+      return env.config.ssh.port if env.config.ssh.port
+      
       # Check if we have an SSH forwarded port
       pnum = nil
       env.vm.vm.network_adapters.each do |na|