Update composer.json for php 7.*

Author: digiltd

composer.json

@@ -13,7 +13,7 @@
     }
   ],
   "require": {
-    "php": "~5.5.0|~5.6.0|~7.0.0",
+    "php": "~5.5.0|~5.6.0|~7.0.0|~7.1.0",
     "bitbull/common-m2": "*"
   },
   "type": "magento2-module",