Merge pull request #18 from drybjed/master

Add option to install GitLab on Vagrant 'master'
Update unattended-upgrades configuration in 'apt'

- you can now define a blacklist of packages which you don't want to
  upgrade automatically;

- you can disable or enable automatic removal of unused packages and
  toggle mail notifications to be sent always (default) or only on errors;
Merge pull request #19 from drybjed/role/apt

Update unattended-upgrades configuration in 'apt'