Fixed #3. Alt for image: logo.

Author: Florian Lautenschlager

_includes/header.html

@@ -3,7 +3,7 @@
         <div class="container">
             <div class="row">
                 <div class="col-lg-12">
-                    <img class="img-responsive" src="img/logo.png" alt="">
+                    <img class="img-responsive" src="img/logo.png" alt="logo">
                     <div class="intro-text">
                         <span class="name">{{ site.title }}</span>
                         <span class="skills">{{ site.subtitle }}</span>