v0.4.1

New features:

• new cool feature: try passing --to-lockfile to cargo upgrade (#337 by @tofay)
• alternative registries support (#336 by @tofay)
• cargo add now supports --rename flag (#345)

Bug fixes:

• cargo upgrade works correctly with renamed dependencies (#342 by @stiiifff)
• cargo-{add, upgrade} now works with ssh auth for git (#334)
• cargo upgrade does not downgrade prerelease dependencies (#348)