more jee support for wtp

I tried the new release 2.3 of the eclipse plugin and noteted that not alle of my paches where included.
I re-pached the 2.3 version again this time i made my changes configurable so they can be turned on and off.

my changes:

• prohibit dupicate entries in the classpath
  provided system paths in combination with log4j/commons-logging/xerces can easely create such problems
• system paths are only included in ears and war when they are inside the project
  bether behavior would be to exclude all system paths because the war and ear plugin also ignore these
• an application.xml specialy for eclipse-wtp
  this makes wtp ears function correctly it includes the eclipse project modules instead of the maven generated jars
• manifest generation for wtp
  wtp needs manifest files, but not the ones maven creates because they have version names for all modules etc
  this generates a wtp manifest that will be in a ons eclipse source directory that is ignored my maven itself

use the parameters -Declipse.wtpmanifest=true -Declipse.wtpapplicationxml=true to acivate the patch.

The manifest generator could be combined with the RadManifestWriter in the future, they are almost the same.

regards,
Ritchie