atomify --serve FTMFW

This was sort of hilariously easy. Was using this as an npm script in my project:

`atomify -j [ index.js:/bundle.js -w -d ] -c [ src/index.css:/bundle.css ] --serve [ --path /example/index.html --open ]`

Other flags supported in `--serve`'s subarg block: 
 * `--st` object that will be passed directly to `st` for configuration, defaults to `process.cwd()`.
 * `--port` Duh.
 * `--path` Path that will be appended to localhost:port when opening
 * `--url` Full url to be opened instead of localhost:port+path
 * `--open` If provided, default browser will be opened when starting the server

Needs plenty more testing and verification before it's merged but pretty sure this is 98% of what we want. :)