JSON Decoding options

- users can now specify all the json_decode params to be used
- additional method added: `Unirest\Request::defaultHeaders`

tests/Unirest/ResponseTest.php

@@ -0,0 +1,28 @@
+<?php
+
+class UnirestResponseTest extends \PHPUnit_Framework_TestCase
+{
+    public function testJSONAssociativeArrays()
+    {
+        $opts = Unirest\Request::jsonOpts(true);
+        $response = new Unirest\Response(200, '{"a":1,"b":2,"c":3,"d":4,"e":5}', '', $opts);
+
+        $this->assertEquals($response->body['a'], 1);
+    }
+
+    public function testJSONAObjects()
+    {
+        $opts = Unirest\Request::jsonOpts(false);
+        $response = new Unirest\Response(200, '{"a":1,"b":2,"c":3,"d":4,"e":5}', '', $opts);
+
+        $this->assertEquals($response->body->a, 1);
+    }
+
+    public function testJSONOpts()
+    {
+        $opts = Unirest\Request::jsonOpts(false, 512, JSON_NUMERIC_CHECK);
+        $response = new Unirest\Response(200, '{"number": 1234567890}', '', $opts);
+
+        $this->assertSame($response->body->number, 1234567890);
+    }
+}