Run core tests head-less also from Maven
Run core tests head-less also from Maven

From Eclipse we run the egit core tests head-less on plain osgi so
there is no need to run them in UI thread nor using UI harness when
running these tests from Maven. 

Change-Id: I84d86b66b2da3a5a1af00b14e1b12ea27ed11aaa
Signed-off-by: Matthias Sohn <446760a3fbea85cd5f8f4f5c3de304fe3a38014f@sap.com>

collaborative-modeling/egit,mdoninger/egit,bols-blue/eclipse_maven_autobuild_sample,chalstrick/egit,bols-blue/eclipse_maven_autobuild_sample,paulvi/egit,paulvi/egit,rickard-von-essen/egit,rickard-von-essen/egit,jdcasey/EGit,SmithAndr/egit,jdcasey/EGit,wdliu/egit,SmithAndr/egit,blizzy78/egit,collaborative-modeling/egit,wdliu/egit