Think about .contrib package

[sobolevn]

We possibly can create a .contrib package with some popular use-case like:

1. Result -> django request converter
2. Result -> transaction rollback
3. etc

Or maybe documentation will be just fine.

I invite @proofit404 to give some ideas.

[proofit404]

contrib package is a great idea.

Maybe we can start with wrapping django rest framework mixins with @safe decorators.

This will allow us to write create, update and destroy actions using @pipeline.

[sobolevn]

Refs #88