(#18) Use more versatile URL handling for getting the chocolatey install script URL

[vexx32]

Two main improvements have been made in this PR:

1. When checking the URL ends with .ps1, make sure we use a non-case-sensitive check (i.e., a URL of the form https://server.com/example/chocolatey.PS1 should still work.
2. If it doesn't end in PS1, look for known patterns in the URL, like the common Nexus pattern of /repository/* which indicates the script should look in a specific repository, rather than just assuming the script is definitely hosted in the server root.

This resolves #18 at least for some of the common cases. We can add more complex handling here if needed in future.

[adilio]

LGTM! 🚀