* remove tokio_current_thread tests
* Review changes:
Removed newline
Moved uds tokio test crate to top to avoid self and keep with convention of other test crates
Removed sleep from uds test and block until all futures are completed.
Refactor multiaddr crate.
- Remove `AddrComponent`. Instead `Protocol` directly contains its
associated data.
- Various smaller changes around conversions to Multiaddr from other
types, e.g. socket addresses.
- Expand tests to include property tests which test encoding/decoding
identity.
* Use `unsigned-varint` crate.
* Implement `Display` for `Protocol`.
Gives `ToString` for free.
* Use `Cow` in `AddrComponent`.
* Add `AddrComponent::acquire`.
* Document `AddrComponent::acquire`.
