Use Markdown mailable for registration mail, fixes OpenDominion#55

app/resources/views/emails/auth/registration.blade.php

@@ -1,2 +1,17 @@
-<p>Thank you for registering to OpenDominion.</p>
-<p>Click <a href="{{ route('auth.activate', $activation_code) }}">here</a> to activate your account.</p>
+@component('mail::message')
+Hello {{ $user->display_name }} and welcome to OpenDominion!
+
+Before you can start playing you need to activate your account:
+
+@component('mail::button', ['url' => route('auth.activate', $user->activation_code)])
+Activate
+@endcomponent
+
+If that doesn't work, try pasting this in the browser: {{ route('auth.activate', $user->activation_code) }}
+
+For reporting issues, use the [issue tracker](https://github.com/WaveHack/OpenDominion/issues) on GitHub.
+
+Have fun playing!
+
+OpenDominion
+@endcomponent

src/Mail/UserRegistrationMail.php

@@ -13,7 +13,7 @@ class UserRegistrationMail extends Mailable
     use Queueable, SerializesModels;
 
     /** @var User */
-    protected $user;
+    public $user;
 
     /**
      * Create a new message instance.
@@ -32,8 +32,6 @@ public function __construct(User $user)
      */
     public function build()
     {
-        return $this->view('emails.auth.registration', [
-            'activation_code' => $this->user->activation_code,
-        ]);
+        return $this->markdown('emails.auth.registration');
     }
 }