support for authsub on youtube_it gem

youtube_it_authsub.rb

require 'rubygems'
require 'youtube_it'

#first get the token user in this link
https://www.google.com/accounts/AuthSubRequest?
      next=callback url
      &scope=http%3A%2F%2Fgdata.youtube.com
      &session=1
      &secure=0

#with authsub
#this create a single-use token
client = YouTubeIt::AuthSubClient.new(:token => "token", :dev_key => "dev-key")

#to exchange a single-use token for a long-lived session token
puts token = client.create_session_token

#for create long token session (first you need create a single-use token then convert to session token)
client = YouTubeIt::AuthSubClient.new(:token => token, :dev_key => "dev-key")


#for revoke a session token
puts client.revoke_session_token

#for get info of session token, allow us see if the session is valid or no
puts client.session_token_info