On develop branch, some Java 8 services warn about memory opts

For example the geonetwork service and also the ones below:

```
spatialhub            | OpenJDK 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0
regions               | OpenJDK 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0
```

Should this OPT be removed?