Support local template
Support local template if template is an exist template tar file.

Here is a simple solution that works for me.

Modify https://github.com/skpm/skpm/blob/b28241db9c978e5173b80de65cf69b7ac682d312/src/commands/create.js#L102

```js
    const archive = await require('fs').existsSync(repo)
 ? Promise.resolve(repo) : gittar.fetch(repo).catch(err => {
      spinner.fail('An error occured while fetching template.')
      return error(
        (err || {}).code === 404
          ? `Could not find repository: ${repo}`
          : (err || {}).message,
        1
      )
    })
```
