Add registration captcha support

templates/register.pug

@@ -36,6 +36,11 @@ block content
           p
             | Providing an email address is optional and will allow you to recover your account via email if you forget your password.
             strong   If you do not provide an email address, you will not be able to recover a lost account!
+        if hCaptchaSiteKey
+          noscript
+            .text-danger This website requires JavaScript in order to display a CAPTCHA.
+          .form-group
+            div.h-captcha(data-sitekey=hCaptchaSiteKey)
         button#registerbtn.btn.btn-success.btn-block(type="submit") Register
   else
     .col-lg-6.col-lg-offset-3.col-md-6.col-md-offset-3
@@ -44,6 +49,8 @@ block content
         p Thanks for registering, #{registerName}!  Now you can <a href="/login">Login</a> to use your account.
 
 append footer
+  if hCaptchaSiteKey
+    script(src="https://hcaptcha.com/1/api.js" async defer)
   script(type="text/javascript").
     function verify() {
       var valid = checkUsername();