Release v2.0.0-beta.0

Version v2.0.0-beta.0

• ACS CLI v2.0.0-beta.0 testing release
• Add ACS CLI version command
• Add ACS Config CLI with subcommands:
  -use-stack, add-stack, current-stack
• Add ACS Login CLI
• Add CLI support for ACS apps management command with subcommands:
  -install, describe, list, uninstall
• Add ACS CLI support for token management command with subcommands:
  -create, describe, delete.