Gem sources

[smellsblue]

Factor gem sources to correspond to upstreams, use Rack middleware to figure out which source to use, and push all meaningful logic out of Gemstash::Web.

[pcarranza]

Hold on on this change. I think there are a few things missing. Let me review better when I get home.

[smellsblue]

@pcarranza thanks for the review! And no rush, I'm not able to work on gemstash till later tonight probably anyways :-)

[smellsblue]

I was also thinking of adding an integration test against the redirect strategy later, I'll push to this branch when I get to it.

[pcarranza]

Just to share a thought, I think we got to the same place with 2 different paths.

The branch I am working with I am basically building the "helper" (which I renamed to HTTPClient), but I am injecting a client builder which knows how to return something that knows how to create a client. This is so basically because of the same thing: we are changing the upstream url.

By injecting this "builder", you can also inject it in testing, and then you don't need to stub the methods to control that in testing. But this is a WIP in my branch still.

[pcarranza]

I like it, I actually like a lot to handle the path parsing in the middleware, but I think that we are spreading the logic of how to handle the upstream (by calling chomp_path from many places) too much.

I think that the concept of the upstream as a concern is there asking to be extracted to a professional object, and that the web_helper is being stretched by not creating an HTTPClient which is what we actually need.

That said, let's move forward because I think that it is a step in the right direction. Then I can rebase my changes on top of this and start injecting the abstractions I already have in my WIP branch.