Make boost animation an SVG that uses SCSS colours

app/assets/stylesheets/components.scss

@@ -663,12 +663,13 @@
   }
 }
 
+@import 'boost';
+
 button i.fa-retweet {
   height: 19px;
   width: 22px;
-  background: image-url('boost_sprite.png') no-repeat;
   background-position: 0 0;
-  transition: background-position 0.9s steps(11);
+  transition: background-position 0.9s steps(10);
   transition-duration: 0s;
 
   &::before {
@@ -678,7 +679,7 @@ button i.fa-retweet {
 
 button.active i.fa-retweet {
   transition-duration: 0.9s;
-  background-position: 0 -209px;
+  background-position: 0 100%;
 }
 
 .status-card {