Make default sing-in logo smaller

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/sections/login.scss

@@ -13,6 +13,10 @@
       max-width: 100%;
       margin-bottom:  20px;
     }
+
+    &.default-brand-image {
+      margin: 0 80px;
+    }
   }
   .login-logo{

app/views/layouts/devise.html.haml

@@ -18,7 +18,7 @@
               .brand_text
                 = brand_text
             - else
-              .brand-image.hidden-sm.hidden-xs
+              .brand-image.default-brand-image.hidden-sm.hidden-xs
                 = image_tag 'brand_logo.png'
               .brand_text.hidden-xs
                 %h2 Open source software to collaborate on code