Get rid of RouterOverlayTrigger and RouterModalTrigger

[taion]

Per react-bootstrap/react-bootstrap#811 (comment)

These won't actually be needed for React v0.14.

[mtscout6]

You sure that you want to remove this before 0.14 is out? Is there anybody that's using it at the moment. I'm fine with creating an issue and a React 0.14 milestone if that's the case.

[taion]

Oops, should have been more clear - I should have done more research before adding those two components, but I agree that we can't remove them until React v0.14 is out. I just wanted to get rid of the docs right now to minimize the number of users for when we do deprecate those components.

[taion]

#98 gets us halfway there.

[taion]

f911799