Fix sense of other check for SITE_PERMISSION_MIDDLEWARE.
Fix sense of other check for SITE_PERMISSION_MIDDLEWARE.

Issue introduced by commit 00f4a63.

stephenmcd/mezzanine,frankier/mezzanine,jerivas/mezzanine,christianwgd/mezzanine,wbtuomela/mezzanine,molokov/mezzanine,jerivas/mezzanine,jerivas/mezzanine,stephenmcd/mezzanine,frankier/mezzanine,dsanders11/mezzanine,dsanders11/mezzanine,dsanders11/mezzanine,stephenmcd/mezzanine,readevalprint/mezzanine,frankier/mezzanine,wbtuomela/mezzanine,wbtuomela/mezzanine,molokov/mezzanine,christianwgd/mezzanine,readevalprint/mezzanine,readevalprint/mezzanine,molokov/mezzanine,christianwgd/mezzanine