Return result of next action

[mbernardy]

This change was necessary for me to get the middleware to work correctly with the middleware provided by redux-thunk and some of our internal middleware.

I am far from a redux pro so please let me know if there is another way to effectively combine this middleware with others.

Thanks for creating this stuff and keep up the good work.

-Max

[Ashoat]

Published updated package at react-navigation-redux-helpers@1.0.1