www/django16: Update DEPRECATED text and EXPIRATION date

Update DEPRECATED text displayed to users to match the verbage used at
upstream [1].

Set the EXPIRATION_DATE to "End of extended support" date + 6 months

While I'm here:

• Improve whitespace alignment
• Add whitespace for readability

[1] https://www.djangoproject.com/download/#supported-versions

Approved by: python (with hat)
MFH: 2015Q3