I need to work on this, the --quiet option only show errors, but the build is long (2785 files to check)
I will add some green dot maybe to know the build is working.

It's working now but the build take 20 minutes

Taking 20 minutes each build is a little hard.
(Our build takes about 10 mins now and I think it is too long...)

IMO rake check:markup should not be included in CI and be used manually.

Maybe check only modified pages or only Time.now.year pages will be faster.

@makimoto It's about 5 minutes now and it check all current year news, which are the most patched/added.

Still need to consider whether it's worth the extra time for each build.

And if we include this check, what about the others? Shouldn't we include them also...?

@stomar
Yes, it's not the best, but it's better than nothing I think right now.
I would be better to have a weekly "complete" build, but I don't think it's possible with travis-ci ?

After thinking it over again: I'm against including this test in every build. The tests should be run manually for gem updates, layout changes, and the like.

The current system with markdown and html templates avoids most of the markup errors.
And new posts are supposed to be proofread in the staging area (which should reveal markdown blunders like missing brackets for links). Faster staging is IMO much more useful than testing every typo fix for html markup errors.

Note that the vast majority of the recent markup fixes (#832) stem from "legacy" content transfered from the previous RadiantCMS site.

You are right about "legacy" markup fixes, feel free to close this PR.