ignore example/sp-wsgi/sp_conf.py
explicitly set binding when calling parse_logout_request_response
expose LogoutRequest.issuer property to fix logging out with redirect
add support for logging out to example/sp-wsgi
Fix example/idp2 logging out with SOAP, POST, or REDIRECT
sign authn and logout requests in the example
SPEC says SP AssertionConsumerService cannot support HTTP-Redirect

This is according to the SAML2 spec, section 4.1.2.
whitespace cleanup
Use a better error message if we find a non-existing session
allow a SP to use the configured name_id_format
Merge pull request #164 from erickt/logout

Add Single Logout support to examples and fix some bugs