Share reconcile transaction in batched updates

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

Test Plan:
grunt test
Improve error for nested render calls

In the future we could consider wrapping the entire public API (renderComponent, setProps, setState, etc) in this check but this should do for now.

Test Plan: grunt test
Guard top-level methods, not in every render call

Test Plan: grunt test
Current set of must-have SVG attributes / tag

The current set of SVG attributes / tag I felt like I needed
them absolutely for my React/SVG editor app.
Add tspan to JSX transform
Fix IE11 collapsed ranges in ReactDOMSelection

In IE10/11, it is apparently possible to have a Selection or Range object that has the following properties:

  - `anchorNode` === `focusNode` (Selection) or `startContainer` === `endContainer` (Range)
  - `anchorOffset` === `focusOffset` (Selection) or `startOffset` === `endOffset` (Range)
  - `isCollapsed` === `false` (Selection) or `collapsed` === `false` (Range)

As defined in http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html, this doesn't really make sense. Since the nodes and offsets are the same, the "collapsed" value should be `true`.

Moreover, when calling `selection.toString()` in this case, it appears that the entire text contents of `body` -- including `<script>` tag contents -- are considered within the selection. I thought maybe the selected nodes were missing from the DOM or something, but no, they're there.

Sidestep all of this in `ReactDOMSelection` by calculating the `collapsed` property manually and setting the selection length directly to zero if it is actually collapsed.

Side note: I think that for selection restoration on contenteditables, we shouldn't try to do this offset calculation. We should just use the structure provided natively (nodes and offsets) since we can restore using that structure as well.
Remove unnecessary tests from insertChildAt and inline it instead
Test innerText/textContent on document.documentElement instead
Merge pull request #879 from syranide/inlinechild

Remove unnecessary tests from insertChildAt and inline it instead
Update build status svg badge
Merge pull request #1450 from sahat/patch-1

Update build status svg badge
Merge pull request #887 from syranide/textdocument

Test innerText/textContent on document.documentElement instead
Fix transition end detection for Android

Some Android versions have the "transition" and "animation" properties
set on element style objects despite not supporting un-prefxied animations
and transitions.  This change adds an additional sanity check to make sure
the correct event handlers are added for transition groups.
Fix perf suite broken by descriptor change
Merge pull request #1452 from chenglou/perf-fix

Fix perf suite broken by descriptor change
Bump jstransform dependency to point at 4.0.1 or higher
Merge pull request #1455 from jeffmo/master

Bump jstransform dependency to point at 4.0.1 or higher
Warn instead of throw for nested render calls
Merge branch 'spicyj-nested-render' from #1402
ReactTransitionGroup: Fix changing to null child

Fixes #1457.

Test Plan: grunt fasttest