Terraform-manager

Added

* Added an optional `-s` CLI flag to tell `terraform-manager` to suppress all output (by [cooperwalbrun](https://github.com/cooperwalbrun))
* Added functionality for the `--execution-mode` operation (by [cooperwalbrun](https://github.com/cooperwalbrun))

Changed

* All operations' reports will now write messages indicating that nothing changed when applicable (by [cooperwalbrun](https://github.com/cooperwalbrun))

Added

* Added a `configuration_is_valid()` method to the `Terraform` class (by [cooperwalbrun](https://github.com/cooperwalbrun))

Changed

* Reorganized CLI operations and started using the new `configuration_is_valid()` method to check CLI parameters (by [cooperwalbrun](https://github.com/cooperwalbrun))
* Updated the argument parser for the CLI to function in a way more consistent with the documentation (by [cooperwalbrun](https://github.com/cooperwalbrun))

Added

* Implemented the `--delete-vars` operation (by [cooperwalbrun](https://github.com/cooperwalbrun))
* The `--lock` and `--unlock` operations will now write descriptive messages about prior lock states in the report (by [cooperwalbrun](https://github.com/cooperwalbrun))

Fixed

* Removed unexpected console output during the `--configure-vars` operation and added unit test assertions to prevent this in the future (by [cooperwalbrun](https://github.com/cooperwalbrun))

Added

* Implemented the `--create-vars-template` and `--configure-vars` operations (by [cooperwalbrun](https://github.com/cooperwalbrun))

Changed

* The Terraform organization must now be specified via the `-o` argument on the CLI (by [cooperwalbrun](https://github.com/cooperwalbrun))

Fixed

* Tokens specified inline via the `Terraform` class's constructor are now used for the working directory operations (by [cooperwalbrun](https://github.com/cooperwalbrun))

Added

* Added an optional `--no-tls` flag to enable Terraform API interactions via HTTP instead of HTTPS (by [cooperwalbrun](https://github.com/cooperwalbrun))
* Added an optional `token` keyword argument to the `Terraform` class's constructor (by [cooperwalbrun](https://github.com/cooperwalbrun))

Changed

* Moved the fetch of workspaces out of the constructor of the `Terraform` class; it will now only occur when needed (by [cooperwalbrun](https://github.com/cooperwalbrun))

Fixed

* The "certain workspaces" message no longer appears inappropriately for the `--version-summary` operation (by [cooperwalbrun](https://github.com/cooperwalbrun))