Prepare for beta 1 (#350)

* Prepare for beta 1

* Added better exception messages

Author: Nyholm

Diff for: CHANGELOG.md

@@ -12,6 +12,7 @@ The change log shows what have been Added, Changed, Deprecated and Removed betwe
 
 - It is now mandatory to pass a client to the `Browser`'s constructor.
 - First argument of `Curl`, `MultiCurl` and `FileGetContent` clients should be the response factory.
+- Using stable version of `psr/http-client`.
 
 ## 0.17.2
 

Diff for: lib/Browser.php

@@ -40,7 +40,7 @@ class Browser implements BuzzClientInterface
     public function __construct(BuzzClientInterface $client, $requestFactory)
     {
         if (!$requestFactory instanceof RequestFactoryInterface && !$requestFactory instanceof RequestFactory) {
-            throw new InvalidArgumentException('$requestFactory not a valid RequestFactory');
+            throw new InvalidArgumentException(sprintf('Second argument of %s must be an instance of %s or %s.', __CLASS__, RequestFactoryInterface::class, RequestFactory::class));
         }
 
         $this->client = $client;

Diff for: lib/Client/AbstractClient.php

@@ -33,7 +33,7 @@ abstract class AbstractClient
     public function __construct($responseFactory, array $options = [])
     {
         if (!$responseFactory instanceof ResponseFactoryInterface && !$responseFactory instanceof ResponseFactory) {
-            throw new InvalidArgumentException('$responseFactory not a valid ResponseFactory');
+            throw new InvalidArgumentException(sprintf('First argument of %s must be an instance of %s or %s.', __CLASS__, ResponseFactoryInterface::class, ResponseFactory::class));
         }
 
         $this->options = new ParameterBag();