Compilation Server

It is a sketch for compilation server (jsx --compilation-server) to improve compilation speed, especially the speed of `make test`.

That's a note on my MBA:

`make test`:

    real   4m48.877s
    user  13m49.013s
    sys    1m43.087s

`time JSX_COMPILATION_SERVER_PORT=1234 make test` (with `jsx --compilation-server 1234`):

    real   2m11.709s
    user  4m31.262s
    sys    0m24.971s


Note that this branch is not yet completed. This pull-req is for reviewing.