fix: building redox in Docker results failure w/ Fuse perms

Created by: jwdeitch

• change /dev/fuse group to redox usr

Problem: [describe the problem you try to solve with this PR.]

On building redox in Docker, I encountered this error:

fusermount: entry for /Users/jordan1/p/redox/build/filesystem not found in /etc/mtab
rm -rf build/filesystem.bin  build/filesystem.bin.partial build/filesystem/
dd if=/dev/zero of=build/filesystem.bin.partial bs=1048576 count=256
256+0 records in
256+0 records out
268435456 bytes (268 MB, 256 MiB) copied, 2.95173 s, 90.9 MB/s
cargo run --manifest-path redoxfs/Cargo.toml --release --bin redoxfs-mkfs build/filesystem.bin.partial
    Finished release [optimized] target(s) in 0.16 secs
     Running `redoxfs/target/release/redoxfs-mkfs build/filesystem.bin.partial`
redoxfs-mkfs: created filesystem on build/filesystem.bin.partial, reserved 0 blocks, size 268 MB, uuid 170dc48d-3f93-4745-b7f1-349eb5cc42f6
mkdir -p build/filesystem/
cargo build --manifest-path redoxfs/Cargo.toml --release --bin redoxfs
    Finished release [optimized] target(s) in 0.14 secs
cargo run --manifest-path redoxfs/Cargo.toml --release --bin redoxfs -- build/filesystem.bin.partial build/filesystem/
    Finished release [optimized] target(s) in 0.14 secs
     Running `redoxfs/target/release/redoxfs build/filesystem.bin.partial build/filesystem/`
redoxfs: opening build/filesystem.bin.partial
redoxfs: opened filesystem on build/filesystem.bin.partial with uuid 170dc48d-3f93-4745-b7f1-349eb5cc42f6
fuse: failed to open /dev/fuse: Permission denied
redoxfs: failed to mount build/filesystem.bin.partial to build/filesystem/: Permission denied (os error 13)
redoxfs: not able to mount path build/filesystem.bin.partial
mk/filesystem.mk:2: recipe for target 'build/filesystem.bin' failed
make: *** [build/filesystem.bin] Error 1

Solution: [describe carefully what you change by this PR.] sudo chgrp redox /dev/fuse:

Change owner of /dev/fuse to redox resolves the issue