V1.3 : New payloads (upper or lower, ^, $@)

Added to level 2 these type of payloads :

• The command name can now have lower or upper letters
• The command name can get "^" (windows only)
• The command name can get "$@" (linux only)

Next steps:

• Rework to have all encoded commands in base64, xxd, rot13 with every types of payloads
• Using threads
• Reverse type of payload (ex: whoami as command argument will give you $(rev<<<'whoami')