www/django1{4,6,7,8}: Reduce diffs between ports

Reduce diffs between Django ports, standardizing on:

• Prefer CHEESESHOP (Geo CDN) over DjangoProject.com for DISTFILES
• Include version and optionally "LTS" in COMMENT suffixes
• De-scope CONFLICTS to CONFLICTS_INSTALL and update match strings
• Whitespace alignment and improve readability
• Use empty(VARIABLE) instead of ! ${VARIABLE}
• Sort Makefile entries (CPE_VENDOR and CONFLICTS_INSTALL)

Approved by: python (with hat)