Rewritten 'athena-start' startup script

- Added a 'status' command line option to check the server's status
- Improved reliability of the start and stop actions, in case the
  pidfiles are present but no longer valid
- Visual improvements
- Note: server messages (other than Error class) are now hidden by
  default.  To show them, look for the line with a "- Show server
  output" and "- Hide server output (default)" comment and toggle them

Signed-off-by: Haru <haru@dotalux.com>