Focusing on LWP here, I'll make a sub-branch for wget and curl, respectively.
Also, grabbed the md5 so that we can validate the downloaded file.

Signed-off-by: Elliot Voris <elliotfriend@gmail.com>
LWP is now downloading, md5-ing, and successfully installing
YNAB4. I'm sure it's not pretty, but it works.

Signed-off-by: Elliot Voris <elliotfriend@gmail.com>