Set different ports for testing in a CI environment (e.g. Jenkins) https://issues.apache.org/jira/browse/OFBIZ-4794

*What's for?*
Finally, OOTB the port offset is interesting in 2 cases:
# To eventually run Sonar on OFBiz sources https://issues.apache.org/jira/browse/INFRA-3590
# To simultaneously run the demos without having to change much things, just one parameter (this will need to have the same commited in R13.07... to be discussed...)

Of course, It can be used for other purposes outside of the ASF context...

*How it's done?*
Basically, I just added a portoffset integer parameter to 3 ant targets (of course this JVM param can also be used in a Java call from command line): start, start-pos, start-both,

The portoffset parameter is set to zero by default in ClassLoaderContainer.java. 
If a value is passed, it's then grabed by Config.java and passed to ClassLoaderContainer.java, where it's set to this value.

 The portoffset is then used to change in one shoot all the default ports values defined (in config or hardcoded), and the admin port value
This is done in following classes:
CatalinaContainer
NamingServiceContainer
ServiceEngine through ServiceLocation
RmiServiceContainer
XMLRPCClientEngine
XmlRpcTests

To avoid hardcoding locations in services definitions, I also created 2 service-locations: main-http and main-soap

*To summarize:* these changes will be used to run "ant start" with a portoffset value which will take care of all ports values, including admin port. For running R12.04 demo as stable we will still need to create a patch for the last time. R13.07 could have a similar patch applied since it's not yet released...

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1533839 13f79535-47bb-0310-9956-ffa450edef68