Fix MySQL download path

[webchick]

Getting this same error referenced in #43 (using macOS Mojave; Version 10.14.6 — master branch of this project; commit hash 664e14f)

     Installing MySQL database on MacOS
Sorry, this target couldn't be completed properly
The error message is:
The following error occurred while executing this line:
/Users/xxx/Desktop/AEM/aem-demo-machine/build.xml:2923: The following error occurred while executing this line:
/Users/xxx/Desktop/AEM/aem-demo-machine/build.xml:3400: Problem expanding gzip Not in GZIP format

Digging in a bit further into build.xml, it looks like lines 2962 and 2964 reference the URL: http://cdn.mysql.com/Downloads/MySQL-5.6/mysql-${demo.mysql}.tar.gz

However, directly accessing http://cdn.mysql.com/Downloads/MySQL-5.6/mysql-5.6.41-macos10.13-x86_64.tar.gz yields a 404 not found. (Which, makes sense that a 404 error would not be in GZIP format. :))

The correct URL seems to be http://downloads.mysql.com/archives/get/file/mysql-5.6.41-macos10.13-x86_64.tar.gz but even after making this change, I'm still seeing the same error, so something else appears to be going on...

[webchick]

Ok, so in debugging from wget, http://downloads.mysql.com/archives/get/file/mysql-5.6.41-macos10.13-x86_64.tar.gz redirects to https, which redirects back to cdn, but a slightly different URL pattern:

https://cdn.mysql.com/archives/mysql-5.6/mysql-5.6.41-macos10.13-x86_64.tar.gz

Changed it to this, and that seems to work!