Improve support for skinny war files

Provide a boolean configuration option for webModules to include the war's transitive dependencies.

As described on http://maven.apache.org/plugins/maven-war-plugin/examples/skinny-wars.html it is very common in a J2EE environment to use so called skinny wars. Here the war's WEB-INF/lib will not contain the dependent jars, but instead they are packaged inside the EAR. The war references them through its META-INF/MANIFEST.MF

This option could be used to avoid the 'painful part' mentioned in the above web page. The war's dependencies wouldn't have to be duplicated alongside the ear's.

I also found an old issue (MEAR-14) which has asked for the current default behavior of not including the transitive dependencies. It suggests a property to include specific dependencies of the war. As far as I can tell this has never been implemented and this is also not what I am asking for. My proposal is an all of nothing kind of option for each war module in the ear.

On a side note, for me this is the part where removal of the old maven 1 style properties per dependency is missed the most. With them it was possible to decide for each single dependency whether to put it in WEB-INF/lib or reference it through the manifest classpath. But of course, then we didn't have the transitive dependencies