messages about expected Java compilation errors

Change-Id: I054234e3adb82896f3085afdfa3c53d9b2016d36
use build --continueonerror

Change-Id: I81a2b01a57641304d0ac59e2960150144dd2ad19
some cleaning in the ant script

Change-Id: I2880334f8b209cec0c4711439bd232fd16363467
added a dep: the tests plugin uses an xtend class in the ui plugin

Change-Id: I1b55c456c5d0c8864350729f9e19685184ea39c9