added 'year descending' to sort options

site/public/index.php

             sort by:
             <select name="sort" id="sort">
                 <option value="relevance">relevance</option>
-                <option value="year">year</option>
+                <option value="year desc">year descending</option>
+                <option value="year asc">year ascending</option>
             </select>
             <input type="submit" id="submit" value="search">
           </form>

site/public/search.php

       sort by:
       <select name="sort" id="sort" onchange="this.form.submit()">
         <option value="relevance" <?php if($_POST["sort"] == 'relevance') echo "selected"; ?>>relevance</option>
-        <option value="year" <?php if($_POST["sort"] == 'year') echo "selected"; ?>>year</option>
+        <option value="year desc" <?php if($_POST["sort"] == 'year desc') echo "selected"; ?>>year descending</option>
+        <option value="year asc" <?php if($_POST["sort"] == 'year asc') echo "selected"; ?>>year ascending</option>
       </select>
       <noscript>
         <input type="submit" class="btn btn-default" value="Set" />

site/solr.php

   }
   else{
     // Assemble a query string to send to Solr. This uses the Solr hostname from config.env. Solr's query syntax can be found at many sites including https://lucene.apache.org/solr/guide/6_6/the-standard-query-parser.html
-    $solrurl = 'http://' . $_ENV["SOLR_HOSTNAME"] . ':' . $_ENV["SOLR_PORT"] . '/solr/' . $core . '/select?q.op=OR&q=content%3A' . $search . '&wt=json&sort=' . $sort . '%20asc';
+    $solrurl = 'http://' . $_ENV["SOLR_HOSTNAME"] . ':' . $_ENV["SOLR_PORT"] . '/solr/' . $core . '/select?q.op=OR&q=content%3A' . $search . '&wt=json&sort=' . urlencode($sort);
   }
 
   // Perform Curl request on the Solr API