Remove dependency from Guzzle (#131)

* Remove dependency form Guzzle

* Fixed borken tests

* Added more tests

* make sure we require httplug as well.

Author: Nyholm

composer.json

@@ -15,14 +15,15 @@
     "fix-style": "php-cs-fixer fix ."
   },
   "require": {
-    "php": ">=5.5.0",
+    "php": "^5.5 || ^7.0",
+    "psr/http-message": "^1.0",
+    "php-http/httplug": "^1.0",
     "php-http/client-implementation": "^1.0",
-    "guzzlehttp/psr7": "1.3.*"
+    "php-http/discovery": "^1.0"
   },
   "require-dev": {
-    "guzzlehttp/guzzle": "6.*",
-    "php-http/guzzle6-adapter": "*",
-    "php-http/message": "*",
+    "php-http/guzzle6-adapter": "^1.0",
+    "php-http/message": "^1.0",
     "mockery/mockery": "^0.9.4",
     "fabpot/php-cs-fixer": "^1.11"
   },