Implement client certificate login

templates/idp/client_certificate.gohtml

@@ -0,0 +1,14 @@
+{{ define "content" }}
+    <p>{{ .IntroText }}</p>
+    <ul>
+        {{ range .emails }}
+            <li>{{ . }}</li>{{ end }}
+    </ul>
+    <p>{{ .RequestText }}</p>
+    <form method="post">
+        {{ .csrfField }}
+        <input type="hidden" name="action" value="cert-login"/>
+        <button type="submit" name="use-certificate" value="yes">{{ .AcceptLabel }}</button>
+        <button type="submit">{{ .RejectLabel }}</button>
+    </form>
+{{ end }}

templates/idp/login.gohtml

@@ -1,6 +1,7 @@
 {{ define "content" }}
     <form method="post">
         {{ .csrfField }}
+        <input type="hidden" name="action" value="password-login"/>
         {{ if .errors.Form}}<p>{{ .errors.Form }}</p>{{ end }}
         {{ if .errors.Email }}<p>{{ .errors.Email }}</p>{{ end }}
         <label for="email">{{ .LabelEmail }}</label>