Bump version to 2.5.0

Minor version bump due to MSRV increase

Version 2.4.0

* Switch from chrono to time (PR #11 by @ShellWowza)
   * Appears to correct a bug in time formatting output
* Upgrade to using Rust 2018
* Bump Minimum Supported Rust Version to 1.53
   * This is a breaking change, required because of the time crate
* Require slog-json version >= 2.6

Version 2.3.0

* Update dependencies

Prepare v2.2.0

(cargo-release) version 2.1.0

version 2.0.0-4.0

version 2.0.0-2.0

version 2.0.0-1.0

version 1.1.1