Make controlled components and bubbling work in IE

Fixes #708.

Test Plan:
In IE9, tested a controlled text input with the event handler on a containing element, as in the fiddle linked in the original issue. Also tested a controlled radio button as the logic there differs within ReactDOMInput. In both cases, I was able to interact with the controls.
Add invariant to check getInitialState return value. Fixes #397
Community Round-up #13
Merge pull request #687 from vjeux/community_13

Community Round-up #13
Merge pull request #739 from jhiswin/master

live_editor.js using deprecated function

Fixes #738 #666
Update parent/child communication tip
Merge pull request #746 from petehunt/tip-update

Update parent/child communication tip
docs tips expose component function
Merge pull request #623 from chenglou/tips-communication

docs tips parent-child communication 2
Make React website work in IE8

Fixes #406.

Empty conditional comment is for http://www.phpied.com/conditional-comments-block-downloads/.
Merge pull request #749 from spicyj/docs-ie8

Make React website work in IE8
docs tips small refactorings
Merge pull request #750 from chenglou/docs-clean

docs tips small refactorings
IE8 style fixes

- Add html5shiv so that HTML5 elements like header, footer, etc can be styled
- Remove a couple uses of :first-child/:last-child which IE8 doesn't support
Merge pull request #752 from spicyj/docs-ie8-css

IE8 style fixes
Making 'native DOM' nodes more explicit in documentation
Merge pull request #753 from vjeux/virtual_dom_docs

Making 'native DOM' nodes more explicit in documentation
Upgrade codemirror and enable line wrapping

Fixes #678.
docs remove link to wiki page

Also some minor writing changes.
Merge pull request #758 from chenglou/docs-kill-wiki

docs remove link to wiki page