Reroll of r9908 (rolled back at r9911): Fixes issue 6189.
WebAppCreator was not scanning war/WEB-INF/lib to fill up .classpath
Added support for windows path separator to testCreatorOnlyEclipseWithJars()

Review at http://gwt-code-reviews.appspot.com/1399801

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9919 8db76d5a-ed1c-0410-87a9-c151d255dfc7