Using Location.replace() for non-html5 init.

https://developer.mozilla.org/en-US/docs/Web/API/Location.replace

Location.replace() will set the location, but not add an item to
history. This means that when we go to /, and director loads #/ on
.init("/"), an item won't be added to the history and back button of the
browser.
Merge remote-tracking branch 'augustl/initial-load-replace' into patches