fix wrong test names for gherkin tests (via #72)

Author: DolgushinG

src/Yandex/Allure/Codeception/AllureCodeception.php

@@ -252,7 +252,7 @@ private function buildTestName($test) {
                 $testName .= ' with data set #' . $this->testInvocations[$testFullName];
             }
         } else if($test instanceof Gherkin) {
-            $testName = $test->getFeatureNode()->getTitle();
+            $testName = $test->getScenarioNode()->getTitle();
         }
         return $testName;
     }