Use jsonutils to load adapter response

This is not technically needed, however we and the libraries we use,
aren't very good about keeping our strings and bytes straight for python
3. jsonutils has an attempt to decode stage that means we can let it
manage the correct types.

Change-Id: I2caf4a5b9a04495aa0286f2b6e3193a17ff246e5
SAML2 ECP auth plugin

Auth plugin authenticating against remote SAML based Identity Providers.
Upon successful authentication the plugin retrieves and stores unscoped token.
Plugin object should be later used for scoping the token.

Currently only HTTP BasicAuth Method is supported as
an IdP authn method.

Will not work for ADFS, as that has extensions to the document formats
as well as a different workflow.

Change-Id: Ieea40505a406bedf7219fa6f9e6cf29a45ad6e88
Implements: blueprint add-saml2-cli-authentication
Merge "Use jsonutils to load adapter response"
Merge "SAML2 ECP auth plugin"