Update Jetty version to 9.4.12 due to 3rd party vulnerability issues in Jetty (CVE-2018-12538, CVE-2018-12536, CVE-2017-7658, CVE-2017-7657, CVE-2017-7656)

Current Situation

• Currently JOC Cockpit uses the Jetty Server version 9.3.11.
• A number of vulnerabilities affect this version, see https://www.cvedetails.com/vulnerability-list/vendor_id-10410/product_id-34824/year-2018/Eclipse-Jetty.html

Desired Behavior

• Due to vulnerability Issues of older Jetty releases the JOC Cockpit should use the current version 9.4.12 that fixes the issues.

Maintainer Notes

• Release 1.11 that includes Jetty Server version 9.3.11 is at its end of life. Therefore no maintenance release is provided.
• Users of release 1.11 should therefore upgrade to release 1.12.