Fix UTF-8 in email

Summary:
Email was not being sent with the right headers/encoding for UTF-8.

Test Plan:
Sent UTF-8 mail using SES, default and SendGrid adapters. SendGrid already
worked; SES and default share the same code so this fixes both.

Reviewed By: slawekbiel
Reviewers: slawekbiel, aran, jungejason, tuomaspelkonen
CC: aran, slawekbiel
Differential Revision: 401

src/applications/metamta/adapter/phpmailerlite/PhabricatorMailImplementationPHPMailerLiteAdapter.php

@@ -24,6 +24,7 @@ class PhabricatorMailImplementationPHPMailerLiteAdapter
     $root = dirname($root);
     require_once $root.'/externals/phpmailer/class.phpmailer-lite.php';
     $this->mailer = newv('PHPMailerLite', array($use_exceptions = true));
+    $this->mailer->CharSet = 'utf-8';
   }
 
   public function supportsMessageIDHeader() {