BUG: Disable units module

Considering Na-mic week is happening next week, we decided to force
the "units" module to be ignored. Waiting the underlying issues are
resolved, this commit will prevent issue #3152 from occurring.

See http://www.na-mic.org/Bug/view.php?id=3152

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22095 3bd1e089-480b-0410-8dfb-8563597acbee