We don't want the log file to be created before command line parsing,
otherwise --version or --help cli option could not work beacause we
don't have permission to write to log file.

lseek was triggering a number overflow by converting long to integer on
its return value

Added specific lseek test

Write errors happenig on deamons are now reported back to clients.
"No space left on device" error is now properly propagated to clients.

Port is only meaningful for some of the communication protocols. For
instance psm2 is not using it at all.

Port can be still specified using the --listen,-l flag:

Example:
```
gkfs_daemon --listen "localhost:1234"
```

margo context id is not the id of the host that send the request. Is the
internal context id of local margo instance.

 - Use regular expression to parse lines
 - More consistent error handling
 - More comprehensive error messages

Implement proper error propagation and handling on get_dirents RPC.
Error happening on the deamon are now embedded on the returned response
and the client throws an exception once he receives the response.