added two ai test helper options: 
  --ai-path <pathname>  : sets the directory for the AI scripts, relative to the Resource Directory; default is "AI"
  --ai-config <string> : a string passed to the AI upon initialization; currently expected to identify an AI config file within the AI directory
These are command-line-only options affecting only the current execution,  not stored in the main FO config file

git-svn-id: svn://svn.code.sf.net/p/freeorion/code/trunk@7775 dbd5520b-6a0a-0410-a553-f54834df5b05