Add ability to easily set the port, number of workers and the app env via the cli.

This PR adds a few options to the start command, all of which are optional and default to the current defaults..

```
trq@oblivion[~/src/php-pm][master]+ ./bin/ppm help start
Usage:
 start [--bridge="..."] [--port[="..."]] [--workers[="..."]] [--app-env[="..."]] [working-directory]
```

No develop branch so I assume sending this to master os cool?