use history.push instead of history.pushState

[gaboesquivel]

ref remix-run/history#168

[kimjoar]

This doesn't work, as far as I can see. The push api is different from pushState, so just changing the name is not enough to get this to work. At least we need all the tests to still pass. You can run them using npm test.

[gaboesquivel]

dammit, I hope it was just an method name change. Sorry about that, I'll check it out and squash the update.

[kimjoar]

Actually, there's already a PR that's solving this problem (and a few other things at the same time): #89