Merge branch '0.5.0' into 'master'

Cargo.lock

Cargo.toml

DESIGN.md

src/allocator.rs

src/archive.rs

src/bin/ar.rs

src/bin/mkfs.rs

src/bin/mount.rs

src/block.rs

src/dir.rs

src/disk/cache.rs

src/disk/file.rs

src/disk/mod.rs

src/disk/sparse.rs

src/filesystem.rs

src/header.rs

src/key.rs

src/lib.rs

src/mount/fuse.rs

src/mount/redox/mod.rs