Allow custom port in CORS check

[AzureMarker]

By submitting this pull request, I confirm the following (please check boxes, eg [X] - no spaces) Failure to fill the template will close your PR:

Please submit all pull requests against the development branch. Failure to do so will delay or deny your request

• I have read and understood the contributors guide.
• I have checked that another pull request for this purpose does not exist.
• I have considered, and confirmed that this submission will be valuable to others.
• I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
• I give this submission freely, and claim no ownership to its content.

How familiar are you with the codebase?:

10

---

Allow a custom port when checking CORS

This template was created based on the work of udemy-dl.

[DL6ER]

Approved.

Tested using Ubuntu 16.04 droplet with lighttpd running on custom port 8080. Everything works (including Disable/Enable, White-/Blacklisting, and the Settings page).