[feature request] Add squirrel user to github

[bajo]

@ipa-nhg @ipa-rmb @mzillich
I would like to get your opinion on this one.

The idea is to have a squirrel account to clone and update the repositories that are cloned with the new install script from Nadia. This user would only need pull permissions and ssh keys added to the squirrel linux user.
With this we can make sure that those repositories are always up-to-date. (cronjob) and nobody would need to work within the squirrel linux account to pull updates.

Any feedback is welcome.
Thanks

[mzillich]

Sounds good to me.
I know that sometimes it is not considered good style to have a non-person user. But as far as I can see it, this is simple and does the job.