Support for routes and address scopes

I've implemented support for routes and also added a scope for addresses. I'm unable to create a pull request (not sure if your repo disables them or is just me vs. gitlab UI).

Anyway please take a look at my fork and tell me what do you think https://gitlab.com/sorki/rtnetlink-hs/commits/master

I relied on older network-simple library that can't handle ipv6 nicely and only returns link local v6 address. For my implementation of ZRE protocol (https://github.com/vpsfreecz/haskell-zre) I need to be able to identify active interface and choose a good default for binding onto (which is the reason for adding routing info). With this package I would also be able to dynamically bind to newly created interfaces.

Cheers, sorki.