A OTP now can be validated via REST service.

Fixed "PHP Fatal error:  Wrong parameters for Exception([string $exception [, long $code [, Exception $previous = NULL]]])" exception."

Other issues:
	Fixed #9 Add ability to set parameter name for the secret key.
	Fixed #6 Removed hard-coded _otp parameter in Listener.
		Xml syntax
		Default value in SingleSignOnFactory
	Fixed #11 404 response when OTP is invalid, added correct on failure redirect with _otp_failure=1 parameter.
		Bump SF2 version, UriSigner requires 2.2 or higher.
		Added url sign when OTP invalid failure redirect occured.
		Compiler pass.
	Fixed #1 EntryPoint::start() and OneTimePasswordListener::attemptAuthentication() is now signed.
		Set fm_sso.uri_signer as public
		Sign /sso/logout uri