Switch back to upstream php-restclient

The bug it has can be avoided by not using `format`,,
which is already automatically detected by the response's Content-Type.

client.php

@@ -7,7 +7,7 @@ class LightningStrikeClient {
   protected $api;
 
   public function __construct($url) {
-    $this->api = new RestClient([ 'base_url' => rtrim($url, '/'), 'format' => 'json' ]);
+    $this->api = new RestClient([ 'base_url' => rtrim($url, '/') ]);
   }
 
   /**

composer.json

@@ -2,12 +2,8 @@
   "name": "elementsproject/lightning-strike-client-php",
   "description": "PHP client for the Lightning Strike REST API",
   "license": "MIT",
-  "repositories": [{
-    "type": "vcs",
-     "url": "https://github.com/shesek/php-restclient.git"
-  }],
   "require": {
-    "tcdent/php-restclient": "dev-master"
+    "tcdent/php-restclient": "^0.1"
   },
   "require-dev": {
     "phpunit/phpunit": "^6.4",