Removed HTTP dependencies (#694)

Author: Nyholm

composer.json

@@ -18,10 +18,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^6.1",
-        "geocoder-php/provider-integration-tests": "^1.0",
-        "php-http/message": "^1.0",
-        "php-http/curl-client": "^1.7",
-        "nyholm/psr7": "^0.2.2"
+        "geocoder-php/provider-integration-tests": "^1.0.1"
     },
     "provide": {
         "geocoder-php/provider-implementation": "1.0"