adjust video size so better for mobile, a=chris

diff --git a/en-US/pages/install.thtml b/en-US/pages/install.thtml
index da23a82..1dad637 100755
--- a/en-US/pages/install.thtml
+++ b/en-US/pages/install.thtml
@@ -11,7 +11,7 @@
         <li><a href="#multiple">Systems with Multiple Queue Servers</a></li>
     </ul>
 <h2 id="demo">Demo Install Video</h2>
-<video width="640" height="480" controls>
+<video style="width:90%;" controls="controls" >
   <source src="YioopDemo.mp4" type="video/mp4">
   <source src="YioopDemo.ogg" type="video/ogg">
   Your browser does not support the video tag.