Logging in a format that is compatible to tools like ElasticSearch

[frederikheld]

Not the highest priority for TreeCam. Would be more interesting if I use logger for other projects.

Idea:

• Logger can already log to console or a file, but the format is more designed to be consumed by humans
• add the option to output logs as JSON or similar to be consumed by log databases like ElasticSearch

Needs investigation to figure out what tools and standards exist that we can/should use.