Added SSL example, bug fixes and upgrade refactor - Fixed a bug where the PeerConfiguration constructor ignored the protocolMode argument and always set the mode to active - Changed the way UpgradeAsync works, it now requires that the peer be in Passive mode, simplifying the logic but potentially a breaking change - Added SslUpgrader.CheckCertificateRevocation - Added SslUpgrader.RemoteValidationCallback - Added SslUpgrader.LocalSelectionCallback - Added an SSL text-protocol example - Moved to 0.6.0