security/rubygem-omniauth-saml: update from 1.5.0 to 1.6.0

• Ensure that subclasses of OmniAuth::Stategies::SAML are registered with OmniAuth as strategies
• Update ruby-saml to 1.3 to address CVE-2016-5697 (Signature wrapping attacks)

Approved by: junovitch (mentor)
Security: CVE-2016-5697
MFH: 2016Q3