fixed composer.json to download the same set of vendors as with use of...

fixed composer.json to download the same set of vendors as with use of composer.lock. that way Piwik can be also installed with Composer as dependency along with its dependencies

composer.json

@@ -33,7 +33,7 @@
     "require": {
         "php": ">=5.3.2",
         "twig/twig": "1.*",
-        "leafo/lessphp": "~0.3",
+        "leafo/lessphp": "0.4",
         "symfony/console": ">=v2.3.5",
         "tedivm/jshrink": "v0.5.1",
         "mustangostang/spyc": "0.5.*",