Merge pull request #2 from php-http/contract_changes

Contract changes

Author: sagikazarmark

composer.json

@@ -12,10 +12,10 @@
     ],
     "require": {
         "php": ">=5.4",
-        "phpunit/phpunit": "~4.4"
-    },
-    "require-dev": {
-        "php-http/adapter-core": "dev-initial_import"
+        "phpunit/phpunit": "~4.4",
+        "php-http/message-factory-guesser": "^0.1@dev",
+        "guzzlehttp/psr7": "~1.0",
+        "th3n3rd/cartesian-product": "^0.3"
     },
     "autoload": {
         "psr-4": {