Fixed issue with server communication

• fixed problem with Growl which did not show up frequently (thanks to Scott Field)
• fixed problem with encoded header information
• fixed issue where unsupported third party plug-in accounts were shown in account list (thanks to Thierry Langie)
• fixed problem Exchange accounts (thanks to Joseph Boloten)
• MailWidget now knows when your Mac was sleeping and checks eMail just a few seconds after wake.