fix(RouterStore): Match RouterAction type parameters

[livthomas]

I am sending a fix for the bug reported as #561.

You should probably consider better names for type parameters (for example R for router state and S for store state) since now T and V are used quite wildly in the code and every time they mean something different. But I did not want to do such big changes.

[coveralls]

Coverage remained the same at 92.813% when pulling c2cfe6f on livthomas:router-action-type into ab5ad56 on ngrx:master.