Fixed #11696: Changed app loading code so that it does not swallow import...

Fixed #11696: Changed app loading code so that it does not swallow import errors that used to be (prior to r10088) raised.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@12950 bcc190cf-cafb-0310-a4f2-bffc1f526a37