Adding PSR package

Nyholm · Nyholm · commit af00486412db · 2017-08-19T09:32:40.000+02:00
diff --git a/composer.json b/composer.json
@@ -17,6 +17,7 @@
     "require": {
         "php": ">=5.4",
         "psr/http-message": "^1.0",
+        "psr/http-client": "^1.0",
         "php-http/promise": "^1.0"
     },
     "require-dev": {
