Add a Filter for the License Management screen URI

[d4mation]

I accidentally forgot to do this. It does not directly matter for now, but I like having this class be more flexible to where we could point it at an alternate EDD store if needed.

[joelyoder]

I was just about to ask if this got added.

[d4mation]

Lol, yeah. It should be added. But it is pretty low priority.

To clarify: This is the URI shown as part of #47. Not the one shown for #40. #40 is part of the Constructor so it could be argued that it doesn't need a Filter, but we could easily add one for it too.