spectators: Add divider before sidebar login/signup buttons.

This slightly improves the visuals of this component.

static/styles/right_sidebar.css

@@ -253,4 +253,8 @@
         width: 100%;
         margin-bottom: 10px;
     }
+
+    hr {
+        width: 90%;
+    }
 }

static/templates/right_sidebar.hbs

@@ -32,6 +32,7 @@
             <div class="only-visible-for-spectators">
                 <div class="realm-description">
                     <div class="rendered_markdown">{{rendered_markdown realm_description }}</div>
+                    <hr />
                     <a href="/register"  class="signup_button color_animated_button">
                         <i class="fa fa-pencil-square-o"></i>
                         <span>{{t 'Sign up' }}</span>