Fix passing down wrong overlay navigation state in OverlayNavigator

[wsxyeah]

We shouldn't pass the down the state directly to the overlay children,
instead, pass the corresponding state in state.routes.

This bug also caused the issue mentioned in #2407.

[mcabs3]

Please fix your lint errors and we can start the review process.

[mcabs3]

/home/circleci/react-native-router-flux/src/OverlayNavigator.js
  25:26  error  Trailing spaces not allowed  no-trailing-spaces
  31:17  error  'routeName' is not defined   no-undef
  31:35  error  Trailing spaces not allowed  no-trailing-spaces
  31:35  error  Missing semicolon            semi

[wsxyeah]

@mcabs3 fixed