BUG: Tests failed bc BRAINS non-rigid registration took too long; EMSegmenter failed if the auto sampling of covariance matrix resulted in 0 entries in the diagonal; Add info to error message to simplify tracing down the issue; Changed one of the Tests so that they only perform affine registration; Fixed naming convention for atlases that are loaded in through api instead of mrml

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23640 3bd1e089-480b-0410-8dfb-8563597acbee