Code cleanup / Quality of Life updates

Adapter::get, post, put, patch and delete all had non-optional parameters for $headers and $query or $body. These have been made optional. I also re-ordered the parameters as $headers was never used while $query/$body were heavily used. I also condensed and removed some duplicate calls so that every call to Adapter::get/post sends that call to Adapter::request. It could use a magic method to do this but it might make it more difficult to test.

tests/Endpoints/IPsTest.php

@@ -18,8 +18,7 @@ class IPsTest extends TestCase
         $mock->expects($this->once())
             ->method('get')
             ->with(
-                $this->equalTo('ips'),
-                $this->equalTo([])
+                $this->equalTo('ips')
             );
 
         $ips = new \Cloudflare\API\Endpoints\IPs($mock);