react router v4 shows same component in modal as well as in background page

[naiduprakash]

After loading the modal when i refresh the page the component is open in a page rather than a modal.
at this moment when i refresh the page twice and go back using the back arrow of browser the component is shown inside the modal as well as in the background page.

[pshrmn]

I wrote the modal example and its location state management definitely isn't perfect, but it is "good enough" to demo the behavior most of the time. If you want to submit a PR that optimizes the behavior across refreshes, please go ahead and do so.