feature request: use the global Promise instead of bluebird

[forivall]

It appears that the main bluebird feature you're using is timeout. In general, it's nice to not force a bluebird dependency.

[joeattardi]

I just released 1.8.0 which removes the Bluebird dependency, and instead uses the global Promise. Please feel free to file another issue if you run into problems with the new release.

[forivall]

Thanks! I wasn't expecting the quick turn around since you seemed a little absent 😅 . Through using the poller in a somewhat novel setup, I found 2 new issues, and filed them at #15 and #16.

Also, I created typescript definitions, (but they're missing the new CANCEL_TOKEN, since you just added that 😄 ).

Thanks for your work!