Add a mechanism to check if servo nightly is up to date

[alex]

I installed a nightly a few days ago, I'd like to be able to check if it's up to date (or maybe even update it directly).

[aneeshusa]

@larsbergstrom is working on an automatic updater.

In the meantime, we push up a new nightly every night. You can get the current version from ./servo --version - would exposing the latest nightly version on the website work so you can check manually? Note that the versions include short git hashes, not build dates, so this only tells you if you are or are not running the latest nightly, not how old yours is. There's no easy way to figure out how old your nightly is without finding that git commit in our master branch.

[alex]

Exposing the version on the website and somewhere in the process (about dialog?) would be great until there is autoupdates.

[cbrewster]

@alex we should have the version exposed in the about window here soon: #12250

[nox]

Was there any progress on that?

[jdm]

Only on mac. Nothing on other platforms or the website.

[atouchet]

Related: #9831