add new "maven" syntax
Surface ls.DefaultClient.http and explain transform operation.

I think it's better to refer to ls's client from G8 rather than
reaching into it from Maven.

And I added a little explanation to `transformProps`.
Override ls's older version of dispatch.

This is a little dicey given the lack of any binary compatibility
guarantee between these versions. It's compiling and testing okay,
better than the last version. (The reason I want 0.11.2 is it behaves
much better when running/testing inside sbt.)
Display a nicer error when we fail to find the maven metadata.

I added some logic to map a 404 response to a `Left` with an
appropriate error message, but this revealed that the left side of
this either was being discarded in fetchInfo where it assigned
`parameters`.

To fix that it I had to do a fair bit of refactoring, and dealt with
some whitespace abuse along the way. There's still a lot that's not
great about the code in g8.scala but at least it does now bubble up
the left side of the `Either` where it should.
Fix compile warning by explicitly constructing tuple.
Some documentation around the maven resolver