The rauc event logger is a separate glib logger that by default logs to
the system console, with annoying ANSI escape sequences. This commit
drops the default stdout/stderr redirect of these log messages and adds
a more exhaustive bundle install and event log, in json format, instead.
For more information about event logging, see the rauc documentation:
https://rauc.readthedocs.io/en/latest/advanced.html
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>