Prefix BLOG_USE_FEATURED_IMAGE in blog templates with settings., otherwise it always evalutes to False.

--HG--
branch : bugfix
Merged in joshcartme/mezzanine/bugfix (pull request #37)

Prefix BLOG_USE_FEATURED_IMAGE in blog templates with settings.
Fix site permissions lookup for non-superusers in admin sites drop-down.
Merge
Bump version to 1.4.1
Added tag 1.4.1 for changeset 422325d0533c