Process manager

It's like the pm2 in Node.js

``` sh
slimane run -i 8 -p 3001 --name slimane-app1
slimane stop `cat /path/to/slimane-app1.pid` # kill -9 `cat /path/to/slimane-app1.pid`
slimane reload slimane-app1 #kill -USR2 `cat /path/to/slimane-app1.pid`
```
