This patch adds "batch" execution of GWTTestCases, significantly reducing the
synchronization and network overhead.

Patch by: amitmanjhi
Review (and simplifications) by: scottb



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5766 8db76d5a-ed1c-0410-87a9-c151d255dfc7