Hide install button by default

client/index.html

@@ -44,7 +44,7 @@
                 <use xlink:href="#notifications" />
             </svg>
         </a>
-        <a href="#" id="install" class="icon-button" title="Install Snapdrop">
+        <a href="#" id="install" class="icon-button" title="Install Snapdrop" hidden>
             <svg class="icon">
                 <use xlink:href="#homescreen" />
             </svg>