Fix error reporting during the evolve command under Django 1.2.
Fix error reporting during the evolve command under Django 1.2.

When printing an exception to the user during the evolve command, we
were passing the exception itself as the text, instead of the exception's
string content. This broke under Django 1.2. Now we cast to a string first.

Fixes bug #116

git-svn-id: 48f3d5eb0141859d8d7d81547b6bd7b3dde885f8@176 8655a95f-0638-0410-abc2-2f1ed958ef3d

clones/django-evolution