Merge pull request #35 from eugene-matvejev/switch_to_php5.6

RC5 - switch to PHP5.6 as PHP5.5 support ends at 10.07.2016

Author: Eugene Matvejev

composer.json

@@ -21,7 +21,7 @@
         }
     },
     "require": {
-        "php": ">= 5.5.9 || 7.0.0 - 7.0.4 || >= 7.0.6",
+        "php": ">= 5.6.0 || 7.0.0 - 7.0.4 || >= 7.0.6",
         "leafo/lessphp": "^0.5",
         "leafo/scssphp": "@dev",
         "leafo/scssphp-compass": "@dev"