add an http.Handler that can wrap a RequestWriter and then call a post processor after http.ServeHTTP has been called
test for wrap abstractions
an http.Handler that keeps track of response code counts using go-metrics
Refactor some error handling helper functions.
Refactor logging http.ResponseWriter names.

The name responseWriter is no good.
Wrap a long log line.
Refactored implementation of CounterByStatus(XX).
Removing old copy of StatusCodeCounted.
Name all the HTTPEquivErrors.
Recreate broken documentation.
This was commented when the second argument was added mechanically.
go fmt
TeeResponseWriter for various post-processing tasks.
Also add TeeHeaderResponseWriter.

Oftentimes, post-processors won't care about the body so we can be more efficient with our memory.
Use TeeHeaderResponseWriter in CounterByStatus(XX).
s/Status/StatusCode/ to be like the standard library.
Refactor PostProcessor to use TeeResponseWriter.

This is a little less flexible than the PostProcessor+ResponseWriterWrapper style but I think in such cases custom handler is essentially necessary anyway and such handlers will have Tee(Header)ResponseWriter available to make their lives easy.
Fix the example; broken since 5f436e4.
Documentation and example for CountByStatus.
Merge branch 'responsecodes'