Add a travis-ci config
Don't run tests on travis

The tests use conduit and trying to come up with an install plan that
includes that package somehow triggers:

    Backjump limit reached (change with --max-backjumps).
Don't run cabal check on travis

The conditional use of -Werror in the .cabal file causes `cabal check`
to fail.
Add missing Httpd module for sdist
Merge travis-ci config changes
Merge branch 'snoyberg-master'