Use native-or-bluebird promises

[jamestalmage]

Apparently there are still some issues with V8's implementation of promises (and others):

1. Aggressive Memory Leak tj/co#180
2. chain of never resolved promises create memory leaks promises-aplus/promises-spec#179
3. Fix memory leak then/promise#67
4. Potential memory leak petkaantonov/bluebird#296

Specifically, the following code quickly blows up with Native Promise implementations (I tried 0.12.7, and 4.1.2 native promises).

function run(i) {
    return  new Promise(function(resolve) {
        setImmediate(resolve);
    }).then(function () {
      return i < 99999999 ? run(i + 1) : i;
    });
}
run(0).then(function (result) {
  console.log(result);
});

This has apparently been fixed in bluebird. I can't find the specific PR, but the above code chugs along (seemingly endlessly) and does not throw when using bluebird. Also, some highly unscientific benchmarking suggests a 2x / 3x performance increase using bluebird (this is echoed by a number of comments I came across on GitHub and SO).

The native-or-bluebird package is really small. It:

1. Checks for bluebird and returns that if found.
2. Checks for native and returns that if found.
3. Throws or returns undefined (depending on how you require it).