RxApacheHttp Bootstrap

[benjchristensen]

RxApacheHttp has been extracted from RxJava prior to 1.0 as per ReactiveX/RxJava#589

I have done this with a simply copy/paste/commit for now. Commit history remains in the 0.20.x branch of RxJava: https://github.com/ReactiveX/RxJava/tree/0.20.x

If anyone wishes to replace the code in this project with files that retain commit history, go ahead and make the changes.

Over the coming weeks the build and release process will be updated.

This project does not need to release immediately as 1.0. It can continue with 0.x releases until it makes sense to hit 1.0. Its lifecycle is now decoupled from RxJava.