Merge pull request #14 from GrahamCampbell/patch-1

Added missing PHP requirement

composer.json

@@ -14,6 +14,9 @@
             "email": "mark.sagikazar@gmail.com"
         }
     ],
+    "require": {
+        "php" : "^5.4 || ^7.0"
+    },
     "require-dev": {
         "phpspec/phpspec": "^2.4",
         "henrikbjorn/phpspec-code-coverage" : "^1.0"