Merge branch 'builds_page_scroll_buttons' into 'master'

Fix bottom position of scroll buttons in build log page

Look at the up/down buttons as well as the **Enable Autoscroll**.

The **Enable Autoscroll** could also be alligned with the right grey box.


## Before

![autoscroll_before](/uploads/f410dc353ca66c338d8a29c7c294758a/autoscroll_before.png)

## After

![autoscroll_after](/uploads/015fdf53618a0d6f468d666de1bbab6a/autoscroll_after.png)


\cc @dzaporozhets @creamzy 

See merge request !1792

app/assets/stylesheets/pages/builds.scss

@@ -21,7 +21,7 @@
 
   .autoscroll-container {
     position: fixed;
-    bottom: 10px;
+    bottom: 20px;
     right: 20px;
     z-index: 100;
   }
@@ -34,7 +34,7 @@
 
     a {
       display: block;
-      margin-bottom: 5px;
+      margin-bottom: 10px;
     }
   }