Share reconcile transaction in batched updates

Should make #1350 better and will also take away any performance hit from #1157.

Test Plan:
grunt test
Adds svg mask and pattern dom components
Added support for itemscope, itemtype, itemprop.
Updated documentation.
ReactTransitionGroup: Fix moving from falsey child

See http://stackoverflow.com/q/23510413/49485.

Test Plan: grunt fasttest
Use camelCase and declare MUST_USE_ATTRIBUTE.
Add support for JSX member expressions <React.DOM.div />
Adds svg pattern and mask components
Merge pull request #1492 from spicyj/rtg-from-false

ReactTransitionGroup: Fix moving from falsey child
Codemod mockDefaultReturnValue

The naming is super confusing.

mockReturnValue -> mockReturnValueOnce
mockDefaultReturnValue -> mockReturnValue
Codemod mockReturnValue externally

320024555cef1b826f8ba9e8bafccad8a5a118e7 didn't update the mocks module
here, just the callsites.
Move tagtree image to docs/

Missed this in #1470
Flux blog post and tutorial
Merge pull request #1499 from vjeux/flux

Flux blog post and tutorial
update Flux tutorial link
Stylistic changes.
Fix minor typo
Update flux-todo-list.md

Fix broken link to todomvc-flux repo

@spicyj cla signed
Start Flux video at 10m21s
Merge pull request #1503 from dybskiy/patch-2

Update flux-todo-list.md