fix(imapextension): Removed from being included

Looking at the code for the latest net-imap gem I see that the
ResponseParser has changed and it includes the tokens this extension was
patching.

lib/gmail/client.rb

@@ -26,7 +26,6 @@ def self.new(name, *args)
       raise UnknownClient, "No such client: #{name}"
     end
 
-    require 'gmail/imap_extensions'
     require 'gmail/client/base'
     require 'gmail/client/plain'
     require 'gmail/client/xoauth'

lib/gmail/client/base.rb

@@ -22,7 +22,6 @@ def initialize(username, options = {})
       # Connect to gmail service.
       def connect(raise_errors = false)
         @imap = Net::IMAP.new(GMAIL_IMAP_HOST, GMAIL_IMAP_PORT, true, nil, false)
-        Gmail::ImapExtensions.patch_net_imap_response_parser
         @imap
       rescue SocketError
         raise_errors and raise ConnectionError, "Couldn't establish connection with Gmail IMAP service"