self-check for latest version?

[adriansev]

Hi! @TimoWilken @ktf given that in the near past there were some build cases solved by
updating alibuild, maybe it would be useful a warning when the used alibuild is not of the latest tagged version? (when installed as not devel mode)
Also, in the same category, also print a warning when alidist is on master branch but not synced with (behind) the origin master?
What do you think?

[ktf]

I think that's not the issue. We already have automatic updates for all the packaged platforms. E.g. on ubuntu you can simply run apt-get upgrade and it will pick up the newest possible version. The issue is that we need to find a better balance between updating the packages too often or too seldom. We will try to be more proactive there.