Merge pull request #73 from avsm/master

Bump to 2.0.0 and depend on Console_unix/Console_xen
Update OPAM dependency on mirage-console-unix to just mirage-console
Merge pull request #74 from talex5/fix-deps

Update OPAM dependency on mirage-console-unix to just mirage-console
move listen_tcpv4 callback to an async thread
(allowing the listener to accept the next client)
unix: fix `Eof on empty TCP.write
Improve opam and travis files
Merge pull request #77 from samoht/master

Improve opam and travis files
Sync for 2.0.0 release
Merge pull request #75 from lnmx/fix-accept

move listen_tcpv4 callback to an async thread
Merge pull request #76 from pqwy/write-errors

unix: fix `Eof on empty TCP.write
Merge branch 'master' of git://github.com/mirage/mirage-tcpip