Jetty mavn plugin run-forked doesn't respect configuration set using file from contextXml option

If one sets option 'contextXml' with a Jetty configuration file where are specified options such as:
1. context path
2. temporary directory
3. base dir
these options are silently overridden with properties from the 'fork.props' file.

The biggest problem is that run-forked goal doesn't support multiple web app resources at all!

I suggest:
1. to check whether JettyWebAppContext instance has already set fields in method org.mortbay.jetty.plugin.Starter.configureWebApp() and set a field only if it is null
2. or to run method configureWebApp() in the org.mortbay.jetty.plugin.Starter.configureJetty method before the JettyWebAppContext instance is populated using 'contextXml' option

Looking at wiki page I believe it says that for instance 'contextPath', if set, will override configuration inside contextXml file. But it's not true. It always overrides it because the field in the Mojo is always initialized with a value and as a result it's always set in the JettyWebAppContext instance.

I think it's fair enough to just show a warning message if an option collides but to use the one from the contextXml file. Although I would not show a warning in case that the mojo is using default values.

Shall I fix this bug by myself and commit it?

Thanks for your support!
Stepan