Support redux v4

[Jameskmonger]

When installing redux-little-router in a project using redux@4.0.1, I get the following warning:

npm WARN redux-little-router@15.1.2 requires a peer of redux@^3.0.0 but none is installed. You must install peer dependencies yourself.

[AllBitsEqual]

Same here. A compat. check and/or update would be great.

In the meantime I'm gonna see if I run into any issues with redux 4 and little-router 15 myself.

[shepmaster]

See also #290

FWIW, we've just been using Redux 4 and everything is fine for our usecases.

[parkerziegler]

Hey folks, as of December 10, 2018, this project is no longer under active maintenance and we will no longer be moving forward with issue requests. Thank you for helping to make redux-little-router better!