Discard optional trailer in chunked responses

I first tried to discard these after reading the last chunk.
Unless I'm misunderstanding the [specs](http://tools.ietf.org/html/rfc2616#section-3.6.1), it looks to me like the CRLF
following the optional trailer should always be sent for a chunked-message.
So after you've read the last chunk (chunk-size line, plus the empty chunk-data line),
you should be able to read until you reach the final CRLF.
But this causes problems with the tests.
The solution here works just as well, as long as we're just discarding the trailer.
But if you decided to merge these into the headers or something,
then this would need to be looked into more closely.

Also, this Regexp will support a HTTP-Version like `HTTP/12.34`,
which would be valid per the specs.