Notable changes

• Add --indentation flag [possible values: 'tabs', 'smart', '<num>'(spaces)].
• Support --diff/-d feature for paths that use space indentation.
• Add update command to update vzit to the latest release.

Changes are reflected in the README's usage section: https://github.com/ttytm/vzit#usage

Full Changelog: v0.1.0...v0.2.0