Add support for related field query (again)

[Mystic-Mirage]

Hi, guys!

I don't think you will accept this PR because it increses minimal Django version to 1.11.

This solution uses custom lookups and custom lookups for related fields only supported since Django 1.11.

So let's wait couple of years before merge :-)

[amitu]

Wonder what is standard solution for this kind of conundrum. May be maintain a two lines of versioning, 0.2.x without this pull request (assuming it works, I haven't tested it yet), and 0.3.x with this pull request: 0.3 only supporting Django 1.11.