Add support for Finagle HTTP servers

This pull request adds preliminary support for Finagle HTTP. It provides constructors and Clojure-friendly wrappers for `Server`, `Request`, and `Response` objects, and basic `ServerBuilder` support. It does not yet attempt to wrap all possible getters and setters.
does naming `->Response` & `->Request` starting with `->` imply that the return value is a record?
vs the convention set elsewhere (e.g. in finagle-clojure.server where `builder` is the constructor fn)