Migrate when -> bluebird

[nfantone]

This is a new take on #158. I realize, since that PR has been seating there for a year and a half now, it won't ever be updated.

I won't add much to what was already commented on #158, except that this time around everything seems to be working fine, including unit tests. No API changes, AFAIK. This should be completely transparent to users. It also gets rid of the so-called "deferred anti-pattern", widely used in the library.

[michaelklishin]

You can verify that rabbitmq-tutorials are still functional with this change just to gather another data point :)

[nfantone]

@michaelklishin Good idea. Also, you made me realize that I didn't remove when from the examples on this repo. I'll add some more commits in a minute.

[nfantone]

@michaelklishin Examples on rabbitmq-tutorials seem to be the same as the ones included in this repo. So, they should work just fine.

[nfantone]

@squaremo Tests running on node 4 threw a TIMEOUT error while trying to connect to the broker. Every other job in the matrix passed just fine.

If you retry the build, it should be good to go.

Also, you should really consider:

• Dropping support for io.js and node 0.8. Both completely unsupported by now.
• Run tests on node 6 LTS.

[nfantone]

@squaremo Also, if you worry about users that may have been using when specific, non-standard, Promise methods, you should know that all of its API is defined in bluebird one way or another. Conversion is trivial.

Here's a quick "migration guide" from when -> Bluebird:

when.done(handleResult, handleError) -> .done
when.then(onFulfilled) -> .then
when.spread(onFulfilledArray) -> .spread
when.fold(combine, promise2) -> .join
when.catch(onRejected) -> .catch
when.finally(cleanup) -> .finally
when.yield(x) -> .return
when.else(x) -> .catchReturn
when.tap(onFulfilledSideEffect) -> .tap
when.delay(milliseconds) -> .delay
when.timeout(milliseconds, reason) -> .timeout
when.inspect() -> .isRejected / .isFulfilled / .isPending / .isCancelled
when.with(thisArg) -> .bind
when.progress(onProgress) (deprecated API)

[squaremo]

I bit the bullet 🎉 I think this warrants a 0.5 release (a minor version bump v1 right?).

Many thanks @nfantone, and to @myndzi for the first time around. And to everyone for being patient, or at least quiet :)

[nfantone]

@squaremo Yey! 0.5.0 seems fine to me, as changes are backwards compatible with minor tweaks. And those changes should only apply if you have been using whenspecific extensions.

[wtgtybhertgeghgtwtg]

It's a little late to say something, but wouldn't it be a better time to just the minimum required node version to 0.12 and use native promises, since support for node 0.10 ended today?

[nfantone]

1. @wtgtybhertgeghgtwtg, sir, you've awarded most unpronounceable name in all Github kingdom.
2. bluebird >>> native Promise. My opinion (and also others' - see this, this and this here).

[wtgtybhertgeghgtwtg]

It's a dependency that duplicates native functionality for negligible and dwindling performance benefits.

[nfantone]

No, it's not.

But you are certainly free to open a new PR with your proposed changes.

[wtgtybhertgeghgtwtg]

If such a PR would be accepted, I would be happy to do so.