GERONIMODEVTOOLS-795: Add support for PortOffset and saving port information into config-substitution file. Also, other improvements to editing server configuration (ensure unsaved changes are not used until saved, and fix undo functionality)

git-svn-id: https://svn.apache.org/repos/asf/geronimo/devtools/eclipse-plugin/trunk@1459957 13f79535-47bb-0310-9956-ffa450edef68