Add Black Lives Matters statement (sass#452)

* Black Lives Matters statement

Swaps top banner out for Black Lives Matter messaging with inline styles for stylistic tweaks since these styles won't need to be added to the main global styles.

* Bold call to action

* Update layout.haml

source/layouts/layout.haml

@@ -48,13 +48,14 @@
         to improve your experience and security.
 
     %header.sl-r-banner(itemtype='http://schema.org/WPHeader' itemscope='itemscope' role='banner')
-      .sl-c-alert.sl-c-alert--info
+      .sl-c-alert.sl-c-alert--info(style='background: #000; padding: 3rem 0; text-align: left;')
         .sl-l-container
+          %h2(style='margin-top: 0;') Black Lives Matter
+
           %p
-            Sass just launched a brand new module system.
-            = succeed '!' do
-              = link_to '/blog/the-module-system-is-launched' do
-                Learn all about the module system on the Sass blog
+            Sass stands with with the protesters against police violence. We encourage our users to 
+            = succeed '.' do
+              %strong get in the streets and join them if you can
 
       .sl-c-pop-stripe
       .sl-l-container