Replace JUnit's setUp/tearDown with gwtSetUp/gwtTearDown to better document and support client code that cannot run in a non-GWT environment.

Suggested by: bruce
Review by: zundel

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2770 8db76d5a-ed1c-0410-87a9-c151d255dfc7