Support for async properties

[akiellor]

I'd like to write properties asynchronous behaviours. My understanding is that testcheck-js doesn't support itat the moment (at least the mocha bridge).

[leebyron]

Unfortunately that would require a complete overhaul of the test runner itself, which expects a synchronous function. It's not possible right now.

[gasi]

+1 for this feature so we could test async functions in testcheck properties.

[leebyron]

Opening this issue to track the demand, however it is still not possible and there are no current plans to build this support.

(Perhaps a great task for someone who wants to take on a challenging PR)

[davidnormo]

I've had a little play: #73, feedback welcome!