Update RUN_DEPENDS: use Django metaport (www/py-django)

• While I'm here:
  • Fix RUN_DEPENDS: add graphics/py-exifread and remove devel/py-pytz
  • Fix version requirement of RUN_DEPENDS
• Bump PORTREVISION for dependency change

Submitted by: sunpoet (myself)
Approved by: Kevin Golding <ports@caomhin.org> (maintainer)