Add reason to blacklist entries on page

Closes OctoPrint#151

Author: foosel

_data/blacklist.yaml

@@ -1,9 +1,11 @@
 #- plugin: identifier of affected plugin, mandatory
 #  versions: list of affected versions (e.g. ["0.1.0"]), optional (all versions if left out)
 #  octoversions: affected OctoPrint versions (e.g. [">=1.2.9,<1.3.0",">=1.3.2"], all versions if left out)
+#  reason: Human readble reason for blacklisting, may contain Markdown
 - plugin: tplinksmartplug
   versions:
   - 0.7.0
   - 0.7.1
   octoversions:
   - "<1.3.6"
+  reason: "[Issue that can render the UI completely non-functional](https://github.com/jneilliii/OctoPrint-TPLinkSmartplug/issues/19)."

assets/css/site.css

@@ -212,6 +212,13 @@ footer {
     width: 25%;
     text-align: center;
   }
+
+  .blacklist-reason {
+    p:first-child::before {
+      content: 'Reason: ';
+      font-weight: bold;
+    }
+  }
 }
 
 // Carbon ads

assets/less/site.less

@@ -35,6 +35,9 @@
                 {% else %}
                 <code>{{ item.plugin | xml_escape }}</code>
                 {% endif %}
+                {% if item.reason %}
+                <div class="blacklist-reason">{{ item.reason | markdownify }}</div>
+                {% endif %}
             </td>
             <td class="blacklist-versions">
                 {% if item.versions %}{{ item.versions | join: ", " | xml_escape }}{% else %}all{% endif %}