Improve logging in db-sync #160

Sometimes it would help to have more information in logs when things go wrong and some debugging is needed:

• when a geodiff error happens when applying a diff, details are missing - e.g. only something like this is reported: "GEODIFF: Error: Conflicts encountered while applying changes! Total 4" -- geodiff also logs the actual changes (as warnings, see e.g. here), but they're not showing in the db-sync log (although GEODIFF_LOGGER_LEVEL=4 should be set) - to be verified why db-sync is not getting more detailed errors

• during pull in db-sync, when taking "Applying new version [no rebase]" branch - it does not say whether updating base or modified file (so when geodiff error happens, it is unclear when exactly it failed)

• db-sync should print config when starting (but remove any passwords - to MM or to DB) so that it's easier to understand the setup