Upgrade tokio, hyper, actix!!

[ferristseng]

Closes #35. Will release as 0.6.0-rc until things stabilize.

• Remove IPFS CLI - Too much effort to maintain this, and no indication that anyone is using it
• Update read.rs to use new stream trait
• Update client.rs to use async/await
  • Updated stream return types to use impl Stream<...> (return is no longer a box)
  • Updated all methods that return a future to use async (return is no longer be a box)
• Update all examples to use async