Use tar for packaging instead of zip

Conflicts:
	oo-install/site_assets/oo-install-bootstrap.sh
Merge pull request #367 from nhr/OSE20_from_zip_to_tar

Use tar for packaging instead of zip
Change portable installer links to .tgz
Merge pull request #373 from nhr/OSE20_from_zip_to_tar

Change portable installer links to .tgz