Fixed RPM package so PID file is stored in /var/run/contextBroker

Implements #612 
Not sure why this line was there, but it seems it has no effect. As far as I understand, it would create the "/var/contextBroker" directory but, after installing package, such directory doesn't exist:

```
[fermin@centollo fiware-orion]$ ls /var/contextBroker
ls: no se puede acceder a /var/contextBroker: No existe el fichero o el directorio
```

Thus, probably this lines has no effect. Anway, it's weird.