update RxJava dependency to 2.x

[gonewest818]

RxJava 1.x is in feature-freeze with an end of life scheduled March 2018. Is there a timeline for this project to update to RxJava 2.x?

https://github.com/ReactiveX/RxJava/blob/2.x/README.md#version-1x-javadoc

[BenWhitehead]

It's not out of the question, however it will depend on RxNetty being updated to use RxJava 2.x since it is the major touchpoint and also the thing doing the heavy lifting for all the connection management stuff.

This looks like the related issue in RxNetty we can follow ReactiveX/RxNetty#593

[gonewest818]

Actually the discussion seems to have played out in other tickets ultimately converging to ReactiveX/RxNetty#566 (can see also ReactiveX/RxNetty#565 and ReactiveX/RxNetty#561)

[gonewest818]

I'll leave this issue in case anyone else finds it useful, but it's no longer relevant to me so I'm unsubscribing.