Add React.batchedUpdates to public API

Fixes #906.
Warn when using hyphenated style property names
add translation for 02-displaying-data.md and change next link in 01-why-react.zh-CN.md
fix some translation bug
Add note about key prop being excluded by cloneWithProps

Whilst this is intentional behaviour (see #1274), it is not documented anywhere, so it is worth mentioning.

It would also be nice if React issued a warning to console if a cloned component loses its key (as this will silently break reconciliation?)
follow docs convention for notes
Update 09.2-form-input-binding-sugar.md

Add better explanation for 2-way data binding to checkboxes using `checkedLink`. As mentionned here: https://github.com/facebook/react/issues/1930
Update 09.2-form-input-binding-sugar.md -> better checkedLink documentation
Cancelling Travis build on commits with docs updates only.

Currently recognized patterns:

* any Markdown files (*.md)
* any files in docs or examples directories.

Closes facebook/react#1768.
Add a 'note' about passing arrays into the `value` attribute

This is for #1700
Add createElement alias for createDescriptor
Fire onBeforeUpdate for space on Android

We deliberately skip the event, but Android Chrome
doesn't fire the keypress, so this is wrong.
Add ={true} so it's aligned with recommended practises
Remove quotes around the `value` attribute
Update ref-01-top-level-api.md

Added docs for `React.isValidClass` and `React.isValidComponent`. 

Still missing top level api:

* `constructAndRenderComponent`
* `constructAndRenderComponentById`
* `withContext`
Merge pull request #2000 from RReverser/stop-travis-on-docs

Cancelling Travis build on commits with docs updates only.
Clarify section introducing `props`
Merge pull request #2016 from samselikoff/patch-1

Clarify section introducing `props`
Clarify section introducing callbacks
Merge pull request #2018 from samselikoff/patch-2

Clarify section introducing callbacks