Add Wercker support

[mrhyde]

Wercker do not provide public api yet so you can call it a "temporary workaround". Because of that build status is only available via Project ID (see example).

P.S. I wasn't able to test the code locally because of dependency hell (i really don't need all that stuff), so we need see what Travis have to say.

Resolves #265

[espadrine]

Thanks a lot!

I chose to use the format /wercker/ci/<id>.svg instead. Tell me if it is fine.

[mrhyde]

Personally i can't understand the use of /ci/ uri segment since none of other services have it (travis, codeship etc.)

[espadrine]

I felt the same way at first. Then, my assumption that a particular brand wouldn't provide more than a single piece of information turned out wrong several times, and the corresponding code increase in complexity as a result.

I can't really change what I shipped, but I try very hard not to forget to add a vendor-specific switch in future URLs. You may notice that most of the services have one.

[mrhyde]

Well, i get your point.
I posted some issue regarding naming convention here
/issues/291

Thanks for accepting this pr so fast 👍

[espadrine]

I understand where you come from. It may have been a direction I'd have taken in the past.

The way I see it, Travis' URI design can easily go wrong, though. Were they to offer a side service, such as code coverage analysis, we would have a hard time offering it with a URI using the same REST paradigm. On the other hand, if we had started out with /travis/t/joyent/node.svg, we would only need to offer /travis/c/joyent/node.svg.

Besides, putting the resource at the end kind of assumes that every vendor uses the same username/project scheme, which is definitely not the case. Many of them have different requirements (Gratipay requires just the username, and code climate additionally requires some information about the git hosting service in use), and sometimes vary in the number of entries to provide (branches are an obvious example, but Travis also has private repositories with completely different requirements, for instance).

I don't have much regret from cases where I used a vendor switch. I do have regrets from those where I didn't use one, and ended up writing nightmarish regexps to have clean, but future-averse, URLs.

I suppose switching order would work, too:

/travis/joyent/node/t.svg
/travis/joyent/node/master/t.svg

Maybe that would have been better. Maybe I am missing something that would have made this harder to maintain. The system I rely on now seems to hold water, at any rate.

[mrhyde]

Can you please copy-paste this answer to the issue i mentioned before? This PR went far beyond original topic :)

By the way, i can't see wercker in production :( Are you using Continuous Delivery?

[mrhyde]

Just tested, its working but you forget to mention it on project page.

[espadrine]

Yep. I usually leave a bit of time for discussion to unravel before making it public.

If all is good, I'll close #291 and make it public in 12h.