Add v2 mail merge support

spec/Vivait/DocBuild/DocBuildSpec.php

@@ -267,7 +267,7 @@ function it_can_convert_a_doc_to_pdf(HttpAdapter $httpAdapter, Cache $cache)
             ->shouldReturn($expected);
     }
 
-    function it_can_mail_merge_a_document(HttpAdapter $httpAdapter, Cache $cache)
+    function it_can_mail_merge_a_document(HttpAdapter $httpAdapter)
     {
         $expected = [];
 
@@ -284,6 +284,23 @@ function it_can_mail_merge_a_document(HttpAdapter $httpAdapter, Cache $cache)
             ->shouldReturn($expected);
     }
 
+    function it_can_mail_merge_a_v2_document(HttpAdapter $httpAdapter)
+    {
+        $expected = [];
+
+        $request = [
+            'source' => 'a1ec0371-966d-11e4-baee-08002730eb8a',
+            'fields' => ['firstName' => 'Milly', 'lastName' => 'Merged'],
+            'callback' => 'http://localhost/test/callback?id=a1ec0371-966d-11e4-baee-08002730eb8a',
+            'access_token' => 'myapitoken',
+        ];
+
+        $httpAdapter->post('v2/mailmerge', $request, [], HttpAdapter::RETURN_TYPE_JSON)->willReturn($expected);
+
+        $this->v2MailMergeDocument('a1ec0371-966d-11e4-baee-08002730eb8a', ['firstName' => 'Milly', 'lastName' => 'Merged'], 'http://localhost/test/callback?id=a1ec0371-966d-11e4-baee-08002730eb8a')
+            ->shouldReturn($expected);
+    }
+
     function it_errors_with_invalid_credentials(HttpAdapter $httpAdapter, Cache $cache)
     {
         $this->setClientSecret('anincorrectsecret');

src/Vivait/DocBuild/DocBuild.php

@@ -276,6 +276,15 @@ public function mailMergeDocument($source, Array $fields, $callback = null)
         ]);
     }
 
+    public function v2MailMergeDocument($source, Array $fields, $callback = null)
+    {
+        return $this->post('v2/mailmerge', [
+            'source' => $source,
+            'fields' => $fields,
+            'callback' => $callback,
+        ]);
+    }
+
     public function getHttpAdapter()
     {
         return $this->http;