Lower ext-uv factory listing

This ties in directly with reactphp/filesystem#112 where if both ext-eio and ext-uv are present ext-uv interferes with ext-eio. By putting it lower in the factory construction method it will favor ext-eio over ext-uv for filesystem I/O is there is also a another event loop extension present.

src/Factory.php

@@ -47,11 +47,6 @@ public static function create()
     private static function construct()
     {
         // @codeCoverageIgnoreStart
-        if (\function_exists('uv_loop_new')) {
-            // only use ext-uv on PHP 7
-            return new ExtUvLoop();
-        }
-
         if (\class_exists('libev\EventLoop', false)) {
             return new ExtLibevLoop();
         }
@@ -64,6 +59,10 @@ private static function construct()
             return new ExtEventLoop();
         }
 
+        if (\function_exists('uv_loop_new')) {
+            return new ExtUvLoop();
+        }
+
         if (\function_exists('event_base_new') && \PHP_MAJOR_VERSION === 5) {
             // only use ext-libevent on PHP 5 for now
             return new ExtLibeventLoop();