Implement LSB exit codes for the status command line option

The sling standalone Java Application supports being run as a service in that it supports three special command line options:

• start – start as a server in the background
• stop – stop a running server
• status – show the status of the running server

To ease implementation of init scripts, the status command line option should exit with status codes aligned with the Linux Standard Base Core Specification as described in http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html:

• 0 if the server is running fine
• 1 if the status command could not be sent or the response not be received (assuming server dead)
• 3 if the server could not be reached, assuming the server not running
• 4 if the server status could not be checked because the control port is not defined on the command line (with the -j option)