There are several moments, you need to address.
First of all I changed mochiweb_acceptor and mochiweb_request public interfaces. Is this acceptable? And if so, should I increment app version in mochiweb.app.src?

Second. I add ability not to configure recbuf value, by setting it to undefined atom. This will instruct gen_tcp to open socket with default OS settings. But I left default value to 8192 bytes, as it was previously, in order not to change anything for existing clients. Should undefined be default value?

And third, I did not wrote any tests for changing recbuf value b/c I am not sure how to obtain result value from the socket, b/c it depends on OS settings, and, say, on MacOS it will report same value as you passed, but on Linux it will be doubled. Don't know about FreeBSD and other zoo. Any advises?

I did force push with backward compatibility functions added, also I returned usage of mochiweb_request:new/5 in tests and in mochiweb_multipart.

Rebased to current master and removed ability to set recbuf size undefined (aka controlled by OS)

Looks great, thank you!