Remove custom attrs properly when setting to null

I don't think this particular codepath was exercised at all (because all the callers call deleteValueForProperty) but this fixes a bug here nonetheless.
add chinese translation for 01-why-react.md
fix some translation error
fix some translation error
Merge branch 'master' of github.com:rayqian/react

Conflicts:
	docs/docs/01-why-react.zh-CN.md
Normalize whitespace for transformed JSX code
Update jasmine-support.js

fix typo in multiple error messages.
fix `(`
make translation better
add translation for getting-started.md
change some translation words
[addons] Renamed update() directives to commands
TodoMVC Flux Example
added dx and dy for laying out text with relative offsets
add `ReactComponentWithPureRenderMixin` to addons
Support `ms` vendor prefix when generating markup
Make EventPluginUtils clear dispatchIDs and dispatchListeners

The other dispatch utils clear these out and I found a bug where they weren't being cleared out.
I'm thinking this should probably be done in the `SyntheticEvent` constructor but at least this way it's consistent. Also, I know no one else uses `executeDispatchesInOrderStopAtTrue` except the `ResponderEventPlugin`.
Add scrolling attribute for <iframe>
Remove leftovers from ReactTransitionGroup rewrite

Looks like while rewriting @petehunt forgot to remove this block.
See: 9ac27cb551b85293d03d334363acd7cf9c77813a
This block used to contain the only `runNextTick` ocurrences in the whole project.
No tests broken after removal, no documentation affected.
Merge branch 'master' of github.com:facebook/react