Updates apple_safari_webarchive_uxss module to serve .webarchive as an HTTP download.

Verify:

> use auxiliary/gather/apple_safari_webarchive_uxss
> set URLS https://browserscan.rapid7.com
> set DOWNLOAD_PATH /download.webarchive
> rexploit

You should be able to go http://localhost:8080/download.webarchive to download the webarchive. After opening the .webarchive file in Safari you should see the captured data in your console.