Fix a path in the web UI

docs/_layouts/global.html

@@ -35,7 +35,7 @@
             <div class="navbar-inner">
                 <div class="container">
                     <div class="brand"><a href="index.html">
-                      <img src="../img/spark-logo-77x50px-hd.png" /></a><span class="version">{{site.SPARK_VERSION_SHORT}}</span>
+                      <img src="img/spark-logo-77x50px-hd.png" /></a><span class="version">{{site.SPARK_VERSION_SHORT}}</span>
                     </div>
                     <ul class="nav">
                         <!--TODO(andyk): Add class="active" attribute to li some how.-->