Fixes exception bubbling for php7 (#39)

Rescues `Throwable` which includes `Exception` and php7 `Error` objects.

Author: Chris Hulton

Runner.php

@@ -119,7 +119,7 @@ public function run($files)
             }
 
             return $resultFile;
-        } catch (Exception $e) {
+        } catch (\Throwable $e) {
             error_log("Exception: " . $e->getMessage() . " in " . $e->getFile() . "\n" . $e->getTraceAsString());
             return $e;
         }

engine.php

@@ -39,7 +39,7 @@
 $results = $server->get_all_results();
 
 foreach ($results as $result_file) {
-    if (is_a($result_file, "Exception")) {
+    if (is_a($result_file, "Throwable")) {
         exit(1);
     }