Add check for import of shiro.ini configuration file

Current Situation

• When a file shiro.ini is found from the JETTY_BASE/resources/joc folder with a 0-byte file size then JOC Cockpit tries to import the file into the database. This results in an error. 

Desired Behavior

• When a file shiro.ini is found with
  • a 0-byte file size then import of the file is denied and the file is deleted,
  • an unreasonable file size > 1MB then import of the file is denied and the file is deleted.
• The JOC Cockpit log includes a respective message about deletion of an invalid shiro.ini file. No actions are taken about the file, no backup is created before deleting the file.