runtime: Fix unique constraint error checks

The sqlite3 version in fedora (3.8) returns a different error string in the unique constraints
failure case than the one in hack/ (3.7). This updates the check to detect both, fixing
one integration check failure on Fedora.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
aufs: Skip tests if aufs not supported

This makes it possible to pass the rest of the testsuite without aufs in the kernel.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)