CB-7067 run jasmine tests individually

`superspawn.spawn` `opts` now take `onstdio` and `onstderr` to
incrementally handle output from child processes.

`npm run jasmine` now runs `jasmine-serial` instead of `jasmine-node`

`jasmine-serial` runs each test that `jasmine-node` would have run
in the same order `jasmine-node` would have run them using
`jasmine-node` with any command-line arguments you pass it (that
`jasmine-serial` supports).

`serve.spec` now skips tests for platforms for which it's missing
the required binaries.