https://github.com/sematext/logagent-js/pull/277

After some old refactoring in 64f435872178ea16357e4bcad13b3a3db63f6802 the function parseLine became unused and still in the code, moreover removeFields parameter from configuration was not working. This PR returns usage of removeFields as it was before the refactoring.

Also fixed a bug with include/exclude parameter (hint: log._SYSTEMD_UNIT !== log[_SYSTEMD_UNIT]).

And also ignore messages in journald not coming from systemd services (I had audit and kernel syslog messages flooding my logs). This is a questionable change applied only to my setup, so please review it.