Supports Guzzle6

* Removed `json` method in favor of `getBody` that is supported by all
   guzzle versions
 * Removed composer.lock (useless for libraries)

.gitignore

@@ -1,2 +1,3 @@
 vendor
 tags
+composer.lock

composer.json

@@ -4,7 +4,7 @@
     "description": "Send your app metrics to InfluxDB",
     "require": {
          "php": ">=5.4",
-         "guzzlehttp/guzzle": "~4|~5",
+         "guzzlehttp/guzzle": "~4|~5|~6",
          "zendframework/zend-stdlib": "~2",
          "zendframework/zend-filter": "~2",
          "zendframework/zend-servicemanager": "~2"

src/Adapter/GuzzleAdapter.php

@@ -52,7 +52,7 @@ class GuzzleAdapter extends AdapterAbstract implements QueryableInterface
     private function get(array $httpMessage)
     {
         $endpoint = $this->getHttpQueryEndpoint();
-        return $this->httpClient->get($endpoint, $httpMessage)->json();
+        return json_decode($this->httpClient->get($endpoint, $httpMessage)->getBody(), true);
     }
 
     protected function getHttpSeriesEndpoint()