Tracking 1.1

Braindump of actions, will expand on these as I go.
- [x] Document breaking API changes
- [x] Make the breaking changes
- [x] `subTreeLike` has been renamed to `subTree`
- [x] `everySubTreeLike` has been renamed to `everySubTree`
- [x] The original `subTree` has been removed, `exact` can be used to get this behaviour back, but I don't recommend you do.
- [x] The original `subTreeLike` has been removed, `exact` can be used to get this behaviour back, but I don't recommend you do.
- [x] removed `findNode`, use `subTree` instead
- [x] removed `textIn`, use `subTree().text()` instead
- [x] removed `fillField`, use `subTree().props.onChange` instead
- [x] removed `findComponent`, use `subTree()` instead
- [x] removed `findComponentLike`, use `subTree()` instead
- [x] `toString()` no-longer expands child components #26
- [x] `reRender()` now takes props instead of a ReactElement.
- [ ] Implement the new APIs
- [ ] .exact()
- [ ] .any()
- [x] .hasClass()
- [ ] Fully document the new & remaining APIs
- [ ] Matchers
- [ ] Selectors
- [ ] Ensure all APIs have decent test coverage
- [x] Extract traversal code into an internal module and test on its own #23
- [ ] Write a migration guide
- [x] Merge to the `master` branch
- [ ] Publish a `beta` to npm
- [x] Standardise with proper linting rules #41