This change adds the ability to format Authelia's log output as JSON.
Example below:
```
{"level":"info","msg":"Logging severity set to info","time":"2020-01-01T00:00:00+11:00"}
{"level":"info","msg":"Authelia is listening for non-TLS connections on 0.0.0.0:9091","time":"2020-01-01T00:00:00+11:00"}
```
* [MISC] Append log file instead of overwriting
If Authelia is restarted when a `log_file_path` is defined upon restart the log file is overwritten as opposed to appending the existing file.
This change ensures that the log file will be appended to, users will need to ensure that they rotate/truncate this over time especially if running in `debug` or `trace`.
* Amend documentation for log_file_path
* [FEATURE] Support writing logs in a file.
* Add documentation about logs file path.
* Rename logs_level and logs_file_path into log_level and log_file_path.
* Update BREAKING.md
Fixes#338
Co-authored-by: Amir Zarrinkafsh <nightah@me.com>
