asyncify promisified functions

[zartdinov]

Most of Promise realisations doesn't contain nodeify method. Here is extention of async wrapper for promisified functions.
For example promise-styled openpgp library functions looks like

openpgp.key.generate(options).then(function(key) {
    // success
}).catch(function(error) {
    // failure
});

And can be easily wrapped to use with favourite async:)

async.asyncify(openpgp.key.generate);

[megawac]

There can be only one value from promise so can you do

callback.call(this, value)

[megawac]

👍 can you add some unit tests (feel free to add a dev dependency for some promise implementation, e.g. NPO/rsvp/bluebird/es6-promise)

[aearly]

We don't want to have the callback call in the try/catch block.

[aearly]

Yep: The failing test is the one that guards against this: https://travis-ci.org/caolan/async/jobs/70115957

[zartdinov]

Done!

[aearly]

You might want to make these tests node-only, because this won't work in the browser.

[zartdinov]

I think node-only for a while, but all tested promise libraries differently support browsers.

[aearly]

It's not the promise implementation, but the require(name) statement that won't work. We can fix the tests for browsers later.