Fix CVE warnings in Tamaya-core: Vertx / Fix project setup for example project 11-distributed

Fix current CVE-alerts in Tamaya-Core:

https://github.com/apache/incubator-tamaya/network/alerts

• Vertx >=3.5.4
  • https://nvd.nist.gov/vuln/detail/CVE-2018-12537
  • https://nvd.nist.gov/vuln/detail/CVE-2018-12541
• Checkstyle >=8.18 - https://nvd.nist.gov/vuln/detail/CVE-2019-9658
  • Plain update does not work - see comment.