Introduce option for encrypting Assertions

• Refactors Assertion creation in application.rb and implements the SamlResponse class.
• Adds encryption functionality to the SamlResponse class for encrypting the Assertion
• Introduces idp_sso_target_url and issuer properties for constructing an AuthRequest in preparation for generating an SAML response

0.5.0

New Features

• Adds an Encryptor class which encrypts a given assertion with the passed certificate
• Adds a SamlResponse class which generates an XML SAML response document based on passed user attributes, IDP and service provider details.

Note: These classes are not yet in use by the gem and were added to support future updates for supporting encrypted assertions. Currently, all assertions are signed but unencrypted.

v0.4.0

NEW FEATURES

• Add FakeIdp.reset! for resetting configuration (4f9d5fa)
• Add support for ::Configuration#additional_attributes (c86c401)
• bin/server executable added to started local Fake IdP server (ec08444)

FIXES

• bin/console is now executable
• bin/setup is now executable
• Removed all references to builder gem

MISC

• TravisCI configuration updated to run for all pull requests (f19058b)
• Update README examples and formatting