Django-cacheops

- do not prevent fast path deletes on not cached models
- minor optimization

- added cache key prefix function
- added .aggregate() caching
- support QuerySet.union() and friends
- added cache_invalidated signal (thx to Kimmo Kiiski)
- cache .first() and .last() on 'get' op
- correctly skip or show nice error message on non-django models/managers
- allow cleaning file cache in non default place
- cache keys no longer change on fields reorder
- fixed .invalidated_update() on updated object versions
- fixed template tags in Django 2.0
- fixed deprecation warnings in Python 3
- use module global CACHEOPS_DEBUG to cache evolving code
- minor optimizations
Backwards incompatible changes:
- dropped Django 1.7 support
- dropped write_only flag
- dropped implicit write_only in .get_or_create(), .select_for_update() and friends
- .iterator() is never cached now
- invalidate_all() works immediately even in transaction
- cached_as(timeout=0) no longer means timeout is ignored/derived from querysets,
use timeout=None instead.

- fixed CACHEOPS_DEGRADE_ON_FAILURE=True

- support Django 1.11
- support Python 3.6
- preliminary support for Django 2.0
- support multidb nested transactions
- fixed pk with default (leonardo orozco)

- better dirty sql heuristic
- fixed on commit sequence issue (thx to Irae Hueck Costa)
- fixed dup field__eq queries (Michał Ochman)

- fixed querysets with custom .iterator() (like django-polymorphic)
- support no argument cached_view
- check that sample is passed into cached_as()