Web Authentication for SAML federated Keystone

Add Specification for Web Authentication

Change-Id: Ib56a424519f457eaef5d9f5bd0b81a80adabdc07
Merge branch 'saml-web-authn' of github.com:fmarco76/keystone-specs into saml-web-authn

Conflicts:
	specs/juno/saml-web-authn.rst

Change-Id: I87efbd1e10153e87ec93f582c52fc80250b2307a
Merge branch 'saml-web-authn' of github.com:fmarco76/keystone-specs into saml-web-authn

merged
Conflicts:
	specs/juno/saml-web-authn.rst

Change-Id: I49abe7ecda4ac2fe1847a5917a8602a643b9e205