Various cleanups

  * make sure all the subprojects we build get an io-streams-haproxy dependency

  * remove warnings

  * blackbox tests: fix a test that was failing on my machine (unexpectedly it
    was connecting to 127.0.0.1 from a source address of 192.168.1.x)
Failing test for bug: date headers not being emitted.
Fix date header bug, restore test coverage to 100%.
Remove bangs from SendFile.hsc (cabal haddock chokes on them), cleanup.
Force the threadWaitWrite thunk in 'sendHeadersImpl' (given buffering, it's difficult to cover otherwise).
Give 'ov' a type in the Monoid instance for Config.
Add some more type signatures to try to stop haddock from freaking out.
Rename Socket.bindHttp -> Socket.bindSocket.
Finish implementing OpenSSL support.
Allow new io-streams.
Fix build for non-SSL.
Don't run sendfile tests in portable mode.
Fix the SSL build I broke earlier. (sigh)