[Improvement Request] Handle htaccess authentication

Hey Kaz:

I hit an issue where a page is currently htaccess protected and the constant contact plugin was returning the error:
Authorization Required

This server could not verify that you are authorized to access the document requested. Either you supplied the wrong credentials (e.g., bad password), or your browser doesn’t understand how to supply the credentials required.

Steps to Replicate:
– Setup htaccess
– Install Constant Contact Plugin
– Setup a constant contact form (used form designer)
– Submit the form

Expected:
The form to submit

Actual:
The form returned the authorization message

https://ww.wp.xz.cn/plugins/constant-contact-api/