async support

[kabirvirji]

Ran into an issue with async functions since utils.getType(options) === 'Function' only checks for regular Functions, and utils.getType(options) returns AsyncFunction for Async Functions.

[bsansouci]

Hey @kabirvirji does the API really work when passed an async function?

[Schmavery]

I also can't imagine this is the only place that checks if a callback is === 'Function'?

[kabirvirji]

@bsansouci I believe it does, that's how I've been using it

@Schmavery The === 'Function' check happens in 8 places, I can add the AsyncFunction check to all of them if you think its a good idea, let me know.

[bsansouci]

Great to hear! Yeah let's update them in all 8 places to make sure you don't run into any more issues later :)

[kabirvirji]

@bsansouci @Schmavery Done, let me know if anything needs a tweak.

[bsansouci]

It looks good! Thanks a lot.