Merge pull request #37 from pdsinterop/fix/add-link-headers

Change WAC::addWACHeaders() to add "Link" headers instead of replacing them.

src/WAC.php

@@ -36,7 +36,7 @@ public function addWACHeaders($request, $response, $webId) {
 			$wacHeaders[] = "public=\"$publicGrants\"";
 		}
 
-		$response = $response->withHeader("Link", '<.acl>; rel="acl"');
+		$response = $response->withAddedHeader("Link", '<.acl>; rel="acl"');
 		$response = $response->withHeader("WAC-Allow", implode(",", $wacHeaders));
 		$this->filesystem->getAdapter()->setFormat($currentFormat);
 		return $response;