Removed HTML tags from CSS comments

Fix for the following issue in Outlook.com:

HTML tags mentioned at all within your email's comments this can render
the email as entirely blank in Outlook.com.
http://answers.microsoft.com/en-us/windowslive/forum/email/blank-emails-
received-to-hotmail-accounts/c51bb275-7372-4ca9-bb40-998bce165a6b?msgId=
de564cee-8cec-49aa-8538-d37be1852284