[Packaging] Install Node 12 instead of 8
[Packaging] Install Node 12 instead of 8

Plus:
- drop support for Ubuntu Precise and Debian Wheezy
- use non-ssl URL for Mono and Dotnetcore packages

Change-Id: Ic4e1ead1cf3046298e985438e562af535fd59e91

sillsdev/ci-builder-scripts,sillsdev/ci-builder-scripts,sillsdev/ci-builder-scripts