Merge pull request #79 from php-http/php7

Update PHPSpec to make builds running on PHP 7

Author: dbu

composer.json

@@ -19,7 +19,7 @@
         "psr/http-message": "^1.0"
     },
     "require-dev": {
-        "phpspec/phpspec": "^2.2",
+        "phpspec/phpspec": "^2.4@dev",
         "henrikbjorn/phpspec-code-coverage" : "^1.0"
     },
     "autoload": {