refactor MatchRule to use equals rather than compareTo for simplicity
Deprecating existing forms of getBody methods

Ultimately Request and Response objects should use Guava's InputSupplier<InputStream> and InputSupplier<Readable>
fixed header handling by NettyMessageAdapter

BetamaxFilters originalRequest does not contain the request headers so they need to be handled in requestPre. We don't want to just create the request delegate there because the HttpObject passed to that method only has a relative URL.