Merge pull request #894 from ericchiang/backport-saml-fix-v2.3.x

connector/saml/saml.go

connector/saml/saml_test.go

connector/saml/testdata/assertion-signed.tmpl

connector/saml/testdata/assertion-signed.xml

connector/saml/testdata/bad-ca.crt

connector/saml/testdata/bad-ca.key

connector/saml/testdata/bad-status.tmpl

connector/saml/testdata/bad-status.xml

connector/saml/testdata/ca.crt

connector/saml/testdata/ca.key

connector/saml/testdata/gen.sh

connector/saml/testdata/good-resp.tmpl

connector/saml/testdata/good-resp.xml

connector/saml/testdata/idp-resp-signed-assertion0.xml

connector/saml/testdata/okta-resp.xml

connector/saml/testdata/two-assertions-first-signed.tmpl

connector/saml/testdata/two-assertions-first-signed.xml