Producing JSON logs?

In Memento v0.4, the JsonFormatter type was converted into a more general DictFormatter which allowed us to drop JSON.jl as a dependency. However, the original behaviour can still be easily achieved by passing in JSON.json to the DictFormatter constructor.

using JSON

push!(
    logger,
    DefaultHandler(
        "json-output.log",
        DictFormatter(JSON.json)
    )
)