swap !=empty for !=nil and update conf.yml

Author: dzoladz

Diff for: _data/conf.yml

@@ -23,8 +23,8 @@ image-attributions:
     creator: Christopher Behrend
     image-title: Buffalo
     image-url: https://VisitBuffaloNiagara.com
-    license-name: ''
-    license-url: ''
+    license-name:
+    license-url:
 
 ########################
 # Program & Schedule

Diff for: _includes/homepage/jumbotron.html

@@ -3,7 +3,7 @@
 
     <div class="hero-image">
         <picture>
-            {% if site.data.conf.hero-image-filename-webp != empty %}
+            {% if site.data.conf.hero-image-filename-webp != nil %}
             <source srcset="/assets/img/theme-images/{{ site.data.conf.hero-image-filename-webp }}" type="image/webp">
             {% endif %}
             <img src="/assets/img/theme-images/{{ site.data.conf.hero-image-filename | site.data.conf.hero-image-source }}" alt="{{ site.data.conf.hero-image-alt }}">

Diff for: attributions.html

@@ -13,11 +13,11 @@
             <h2>Image Attributions</h2>
 
                 {% for attribution in site.data.conf.image-attributions %}
-                    <h3>{{ attribution.creator }}</h3>
-                    {% if attribution.image-title != empty and attribution.image-url != empty %}
+                    <h3 class="h4">{{ attribution.creator }}</h3>
+                    {% if attribution.image-title != nil and attribution.image-url != nil %}
                     Image: <a href="{{ attribution.image-url }}">{{ attribution.image-title }}</a> <br />
                     {% endif %}
-                    {% if attribution.license-name != empty and attribution.license-url != empty %}
+                    {% if attribution.license-name != nil and attribution.license-url != nil %}
                     License: <a href="{{ attribution.license-url }}">{{ attribution.license-name }}</a> <br />
                     {% endif %}
                 {% endfor %}