Pass LoginServlet's ServletContext to the Authenticators. When implementing SAML validation we need a way to configure a trusted key, and passing the ServletContext seems to be about the simplest way to do this.

<?xml version="1.0" encoding="UTF-8" ?>
<rest-server>
    <!--  The port which the ArtifactDatabase (ArtifactServer) will bind to. -->
    <port>8181</port>
    <listen>localhost</listen>
</rest-server>