[NEXUS-5808] Use sisu-emailer 1.7.2-SNAPSHOT
[NEXUS-5808] Do not even send email if configured SMTP settings are the default ones (=SMTP not configured)
[NEXUS-5808] Improve logged/exception message
[NEXUS-5808] Do not compare default password in order to send or not email
Merge pull request #83 from sonatype/NEXUS-5808-log-email-failure

REVIEW: [NEXUS-5808] Log all emailing exceptions