v3.0.3 - Major upgrade (2.x is stable too)

This release does two major things:

1. It moves all withXXX function into the Request module
2. It changes everything from Async to Hopac's Job
3. HttpFs.Composition that contains the beginning of filters/middleware. v3 doesn't take that all the way, so Composition should not be considered a stable API at this point.

This may or may not be what you're after, so that's why you can also use the 2.x releases if you wish.

That said, you can fairly easily change a Job to an Async with https://hopac.github.io/Hopac/Hopac.html#dec:val%20Hopac.Extensions.Async.Global.ofJob

The aim of v3 and v4 as they come is:

1. Introduce a custom TCP and HTTP parsing stack, replacing the built in ones
2. Introduce support for lots of different useful filters (e.g. a filter for Hawk-signing, Oz-authentication/redirects, Server Sent Events, optimistic concurrency control, request id generation for idempotence. And so on...)