TravisCI: Test neko and macro.
Properly exit with non-zero exit code when test fails.
TravisCI: test php.
TravisCI: show commands and their exit code.
TravisCI: also print stderr.
TravisCI: fixed php testing, allow it to fail.
TravisCI: test cpp.
TravisCI: fix cpp testing.
Merge pull request #2391 from andyli/travis

TravisCI: run neko/macro/php/cpp tests