Fix errors due to "+" in email address. (#1602)
Fix errors due to "+" in email address. (#1602)

- Container names allow only [a-zA-Z0-9][a-zA-Z0-9_.-]
- This fixes an issue with email address containing "+"
Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines