feat(json): json pecl extension may be available all the time

.gitignore

@@ -1,6 +1,7 @@
-.idea
 .DS_Store
+.idea
 build
-vendor
 composer.lock
 composer.phar
+coverage
+vendor

composer.json

@@ -8,8 +8,10 @@
   "author": "Mashape <opensource@mashape.com> (https://www.mashape.com)",
   "require": {
     "php": ">=5.4.0",
-    "ext-curl": "*",
-    "ext-json": "*"
+    "ext-curl": "*"
+  },
+  "suggest": {
+    "ext-json": "Allows using JSON Bodies for sending and parsing requests"
   },
   "require-dev": {
     "phpunit/phpunit": "~4.4",

src/Unirest/Response.php

@@ -25,12 +25,14 @@ class Response
         // make sure raw_body is the first argument
         array_unshift($json_args, $raw_body);
 
+        if (function_exists('json_decode')) {
             $json = call_user_func_array('json_decode', $json_args);
 
             if (json_last_error() === JSON_ERROR_NONE) {
                 $this->body = $json;
             }
         }
+    }
 
     /**
      * if PECL_HTTP is not available use a fall back function