SqlDateCompiler is removed in django 1.8

[karthikbgl]

Django 1.8 no longer has the class SqlDateCompiler, so we might have to modify the code to accommodate that.

https://github.com/jmoiron/johnny-cache/blob/master/johnny/cache.py#L412

[BertrandBordage]

Johnny-cache isn’t supported anymore, use django-cachalot instead.