Allow HTTPlug 2.0 (#903)

Author: Nyholm

src/Http/composer.json

@@ -14,7 +14,7 @@
     "require": {
         "php": "^7.0",
         "willdurand/geocoder": "^4.0",
-        "php-http/httplug": "^1.0",
+        "php-http/httplug": "^1.0 || ^2.0",
         "psr/http-message": "^1.0",
         "php-http/message-factory": "^1.0.2",
         "psr/http-message-implementation": "^1.0",