Added rules to run terraform init before terraform plan or apply (#924)

* Run terraform init to initialize terraform modules

* Fix indent

* Add unit tests for terraform_init.py

README.md

@@ -286,6 +286,7 @@ following rules are enabled by default:
 * `sudo_command_from_user_path` – runs commands from users `$PATH` with `sudo`;
 * `switch_lang` – switches command from your local layout to en;
 * `systemctl` – correctly orders parameters of confusing `systemctl`;
+* `terraform_init.py` – run `terraform init` before plan or apply;
 * `test.py` – runs `py.test` instead of `test.py`;
 * `touch` – creates missing directories before "touching";
 * `tsuru_login` – runs `tsuru login` if not authenticated or session expired;