Merge pull request #8 from chen-ran/master

Support mailgun

.env.example

@@ -31,6 +31,8 @@ MAIL_PASSWORD=null
 MAIL_ENCRYPTION=null
 MAIL_FROM_ADDRESS=null
 MAIL_FROM_NAME=null
+MAILGUN_DOMAIN=
+MAILGUN_SECRET=
 
 AWS_ACCESS_KEY_ID=
 AWS_SECRET_ACCESS_KEY=