Support adding a new connector to tomcat server.xml in Artifactory docker images

Currently we have env variables for configuring the Artifactory tomcat port or max tomcat threads or any additional properties to the tomcat connector. But there is no env variable that can be used to add a new tomcat connector to the server.xml.

The additional tomcat connector is useful in cases where a user wants to configure SSL on the tomcat.

https://www.jfrog.com/confluence/display/RTF/Installing+with+Docker#InstallingwithDocker-TomcatServer.xml