Batch all editor updates together automatically via process.nextTick
Default EditorComponent to updating synchronously in specs

This commit adds a static property, EditorComponent.performSyncUpdates,
which can be used to control the update behavior of all editor
components. In addition, an instance property called performSyncUpdates
be assigned to control the update behavior of a specific instance.
Emit events *after* update to prevent requesting update during an update

When updating synchronously in specs, we can't get away with requesting
an update before the previous update is completed. If we emit events
before the update, we have the potential for one of those events to
cause this to happen. Moving them to after is more correct anyway.
Only forceUpdate of EditorComponent on nextTick if it's mounted
Update markdown-preview to fix specs
Merge pull request #2681 from atom/ns-react-batch-updates

Batch all editor updates together automatically via process.nextTick