* Continue setup even if a file to delete is not found
For various reasons, `.gitkeep` may be deleted already.
(In my case, even though I followed the [Getting Started](https://quartz.jzhao.xyz) instructions exactly, my first run resulted in an `fatal: 'upstream' does not appear to be a git repository`)
If we try to delete `.gitkeep` again and don't ignore `ENOENT`, then the whole setup fails.
* Use fs.existsSync
002bbc37b1