v0.2.1

Implement TerraformCommand which is used to invoke various Terraform commands.

Currently, supports version and all main commands (init, validate, plan, show, apply and destroy),
returning a CommandResult object. The CommandResult object has the following properties:

• retcode indicates the command return code. A value of 0 or 2 is normal, otherwise is abnormal.
• value represents command output. If json=True is specified when executing the command, the output will be loaded
  as json.
• json indicates whether to load the output as json.
• error indicates command error output.