v0.2.0

• Add cargo-upgrade, a brand new subcommand for all your upgrading needs
• Deprecate cargo-list, use the cargo-tree crate instead
• Refactorings and dependency updates
  • No more curl (we use reqwest now)
  • serde 1.0
  • toml 0.4 (still messing up your carefully formatted Cargo.toml files, sorry)