Update lowest versions

Author: shulard

composer.json

@@ -12,8 +12,8 @@
     ],
     "require": {
         "php": ">=5.4",
-        "php-http/httplug": "^1.0",
-        "php-http/message-factory": "^0.3",
+        "php-http/httplug": "^1.0.0-alpha2",
+        "php-http/message-factory": "^0.4@dev",
         "react/http-client": "^0.4"
     },
     "require-dev": {