Have `flambe serve` start a compilation server for EVEN FASTER builds.

Like 50% faster. This brings a tear to my eye:

    $ time flambe build flash
    Building: build/web/targets/main-flash.swf
    haxe --connect 6000 -lib flambe -cp src -main urgame.Main -dce full --no-traces --flash-strict -D native_trace -swf-header 640:480:60:000000 -lib hxsl -swf-version 11 -swf build/web/targets/main-flash.swf

    real    0m0.365s
    user    0m0.192s
    sys	    0m0.032s
Ensure `flambe serve` is run from a project directory.