Fix race condition on authorization

[xAockd]

#76

[FZambia]

Looks like you forgot to include part of your fix into this pr - _subscribeXHR is always null here. Anyway I'll try to extend this to generic case, thanks!

[xAockd]

Omg, yes. I'll add it early in the morning

[FZambia]

@xAockd could you please check #78 instead - I tried to extrapolate your solution to other cases. Also additionally check client ID to be actual.

[xAockd]

@FZambia I've checked your PR. Really good job, very fast reaction on the issue! It should solve the issue and it covers all requests. But, I think that we have to improve the code and follow DRY principle.
If it's okay to you, can we merge it and think about improvenments later?
Thanks

[FZambia]

Thanks for looking. Yep, agree with you about dry - let's merge it anyway, will appreciate pr fixing code repeatition. I am a bit busy at work these days and work on Swift client and investigating possible Java client for Centrifugo at spare time at moment so any help is much appreciated