gear status doesn't work if systemctl is not in /usr/bin/systemctl but /bin/systemctl (and /bin != /usr/bin)

The problem (on a debian system):

```
# gear status mail-1                                                                                                                         
container_status: Unable to fetch container status logs: fork/exec /usr/bin/systemctl: no such file or directory
```

The workaround:

```
ln -s /bin/systemctl /usr/bin/systemctl
```
