Remove fs_extra (#655)

* WIP Remove fs_extra

* Finish removing fs_extra

scripts/copy.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+set -ex
+cargo fmt
+cargo build --release --example copy
+rm -rf test
+mkdir test
+cp -a samples test/a
+mkdir test/a/link
+touch test/a/link/a
+ln -s a test/a/link/b
+mkdir test/a/perms
+touch test/a/perms/400
+chmod 400 test/a/perms/400
+touch test/a/perms/600
+chmod 600 test/a/perms/600
+touch test/a/perms/700
+chmod 700 test/a/perms/700
+time target/release/examples/copy
+ls -lR test
+meld test/a test/c