Merge pull request json-schema-org#30 from stefk/patch-1

Add php validator reference

Author: Relequestual

implementations.html

@@ -61,6 +61,7 @@ <h3>PHP</h3>
 		<li><a id="link-impl-jsv4-php" href="https://github.com/geraintluff/jsv4-php">jsv4-php</a> - <em>supports version 4</em>  (Public Domain / MIT)</li>
 		<li><a id="link-impl-php-json-schema" href="https://github.com/hasbridge/php-json-schema">php-json-schema</a> (MIT)</li>
 		<li><a id="link-impl-json-schema" href="https://github.com/justinrainbow/json-schema">json-schema</a> (Berkeley)</li>
+		<li><a id="link-impl-jval" href="https://github.com/stefk/jval">JVal</a> - <em>supports version 4</em>  (MIT)</li>
 	</ul>
 
 	<h3>.NET</h3>