{dir,store}/filesystem: use filepath.Join instead of +

This fixes listing subdirectories and reading files, which previously failed
with an error message such as “/home/michael/i3statustravis: not found” when
specifying root=/home/michael/i3status, as the root gets Cleaned.

Change-Id: I4a27131b7ab91e6f38e78b42466a30aa372a5088
Reviewed-on: https://upspin-review.googlesource.com/9600
Reviewed-by: Andrew Gerrand <adg@golang.org>
3 files changed
tree: 4d0b2251a04cf04a2f54693f1c56fad5604b675f
  1. README.md
  2. client/
  3. cmd/
  4. dir/
  5. store/
README.md

Experimental components

This directory contains components that are experimental or under development.