Update fasd

Note for fasd:

Existing fasd plugin doesn't even work properly.

- No fasd_cd
- No default aliases (f, a, s, d, z, zz, ...)

So I forked it and totally rewrote it. Please consider it as different
plugin.

db/pkg/fasd

-https://github.com/wa/pkg-fasd
+https://github.com/oh-my-fish/plugin-fasd