CLI install exited with 0 status code

CLI install exited with 0 status code

The CliInstaller used the '0' exit code whenever the status was not OK.
That makes third party script assuming the install actually ran fine
since a 0 exit code is mostly considered as a success. By sending an
error code > 0 (here 1), our automatic installers will be able to catch
the failure and stop proceeding.

I had that issue with a Jenkins job which ran the CLI installer and kept
continuing although there was an error about LocalSettings.php already
existing.

Change-Id: I4f4727df85c09c0a04e4630df91c6213dfce6e9a