Journal rankings

[MikeLydeamore]

It looks like the data for the journal rankings is curated over here:

https://github.com/robjhyndman/Rcademy/tree/master

We will need the abdc and the monash data objects.

We can add this as a dependency for our package, so that the data loads in directly. See usethis guide, then we can reference these objects when we need them in our functions.