Replaces "Spark" word in nav bar with logo.

docs/_layouts/global.html

@@ -38,7 +38,7 @@
                         <span class="icon-bar"></span>
                         <span class="icon-bar"></span>
                     </a>
-                    <a class="brand" href="{{HOME_PATH}}index.html">Spark</a>
+                    <a class="brand" href="{{HOME_PATH}}index.html"></a>
                     <div class="nav-collapse collapse">
                         <ul class="nav">
                             <!--TODO(andyk): Add class="active" attribute to li some how.-->

docs/css/main.css

----
----
 /* ==========================================================================
    Author's custom styles
    ========================================================================== */
 
-/*.brand {
-  background: url({{HOME_PATH}}img/spark-logo.jpg) no-repeat left center;
+.navbar .brand {
+  background: url(../img/spark-logo-100x40px.png) no-repeat left center;
   height: 40px;
   width: 100px;
+  padding: 0px;
 }
-*/
 
 body #content {
   line-height: 1.6; /* Inspired by Github's wiki style */