NMS-6798: Add procmail and postfix syslog definitions

- Added Syslog event definitions for Procmail
- Added Syslog event definitions for Postfix
- Added Syslog uei match definition for Procmail
- Added Syslog uei match definition for Postfix
- Included both event definitions in eventconf.xml
- Included both UEI match definitions in syslogd-configuration.xml
- Normalized XML files with xmllint --format

JIRA: http://issues.opennms.org/browse/NMS-6798

Todo: 
- [x] XML formatting
- [x] Run configTesterTest
- [x] Review proposed pull requests
- [ ] Merge