Move pretty_env_logger to dev-dependencies, it's not useful to crates depending on us.
Move pretty_env_logger to dev-dependencies, it's not useful to crates depending on us.

Also removes chrono configuration, which was only used by `pretty_env_logger`. Everything still runs fine.

Note: needs #35 before `cargo test` can run.

pimeys/apns2,pimeys/apns2