Use larger icon on register.html

// FREEBIE

register.html

@@ -10,7 +10,7 @@
     <div class='container'>
       <div class='row'>
         <div class='col-xs-2 col-md-1'>
-          <img id='textsecure-icon' src='/images/icon_128.png'/>
+          <img id='textsecure-icon' src='/images/icon_250.png'/>
         </div>
         <div class='col-xs-10 col-md-11'>
           <h1>Create your Signal Account</h1>