Slightly improve travis-CI job

This adds GHC 7.0.4 as well as GHC HEAD to the matrix, whereas GHC HEAD failures are tolerated.
Merge pull request #57 from hvr/master

Slightly improve travis-CI job
Enable FlexibleContexts for Network.Browser

This is needed for GHC HEAD (and the future GHC 7.10)

For more details, see

  http://permalink.gmane.org/gmane.comp.lang.haskell.glasgow.user/24612
Merge pull request #58 from hvr/ghc-t8883

Enable FlexibleContexts for Network.Browser
Switched from obsolete gethostbyname() to getaddrinfo()

Neat side-effect: IPv6 is now supported as well.
Updated tests for both IPv4 and IPv6 testing.

Your hosts file should list ip6-localhost as "::1" for the tests to work
correctly. This problem may be solved by modifying the parser in a way that it also accepts
addresses like "[::1]".

Shed is only tested using IPv4, warp is tested using both protocols.
Make the tests pass on Windows.

Windows can't stand high arguments to listen.

The reuse socket options doesn't work on Windows.

"ip6-localhost" is not defined on windows, use localhost instead.