Migrate to chef's libarchive

[dginev]

Based on the discussion here:
fnichol/libarchive-rust#2

The custom fork of libarchive I maintain is something to walk away from and use the chef-maintained official crate instead. Non-critical, as the current fork is operational, but as libarchive gets updated, the wrapper needs to stay up-to-date and I don't think I would have the time+expertise to maintain that one.

[dginev]

This issue is now high priority, as the old libarchive implementation is not workable with rust nightly 1.33.

Would either need to change crates here, or maintain a fork of libarchive-sys, which I really would rather not.

[dginev]

And back to low-priority again -- there was an easy flag to keep the old libarchive fork operational with rustc 1.33. There isn't really any active libarchive crate at the moment, so I don't feel too motivated to jump to the alternative crate today...