Merge pull request #60 from BingAds/v11-12-1

Add v12 support

Author: eric-urban

composer.json

@@ -6,7 +6,7 @@
     "type": "library",
     "homepage": "https://github.com/BingAds/BingAds-PHP-SDK",
     "require": {
-        "php": ">=5.5",
+        "php": ">=5.6",
         "ext-curl": "*",
         "ext-openssl": "*",
         "ext-soap": "*"