Don't escape slash; it's unnecessary

Fixes #1444.

Test Plan: grunt fasttest
Update todo example. fixes 'Create' that shouldn't happen

Currently, an `onBlur` creates a new todo on `TodoTextInput`. This makes sense for existing items but not for new items. I.e consider the following: 

1. cursor on new item ("What needs to be done?")
2. click 'x' on the first item. 

This results in two actions being fired: 

1. TODO_CREATE, with an empty string as 'text'
2. TODO_DESTROY

The proposed fix doesn't send a TODO_CREATE if `text.trim() === "")`
Removes value from rendered attributes of textarea
Fix ReactEmptyComponent disappearing and throwing in IE8
Correctly trim strings for css properties

* If a unitless value is passed with a space it'll return `1 px`
Merge pull request #1495 from syranide/ie8noscript

Fix ReactEmptyComponent disappearing and throwing in IE8
[Docs] Render `null` returns noscript now
Following #1495.
Add helpful message about pooled classes

Hopefully this will make fewer people confused at all of the null properties. The string won't wrap nicely so I tried to keep it pithy:

https://s3.amazonaws.com/uploads.hipchat.com/6574/26709/v8vzKAC784QMkX2/upload.png
Remove timing metrics from Transaction

No one uses these and they weren't meant to be left in.

Test Plan: jest
Adds empty onChange handler to textarea test
Merge pull request #1664 from spicyj/warn-pooling

Add helpful message about pooled classes
Merge pull request #1737 from spicyj/notime

Remove timing metrics from Transaction
Simple custom 404 page.

Github doesn't let us handle 404s within a project repository, so we
handle them at the organization level. In order to handle graceully for
specific projects, we're setting up redirects to projects' own 404.html.
2 docs fixes.

Fix 404 and extra slash in url
Merge pull request #1716 from somethingkindawierd/master

Removes value attribute from rendered html of textarea
Remove unused properties from ReactMount

(useTouchEvents lives in EventPluginUtils.)

Test Plan: jest
Merge pull request #1741 from spicyj/mount-unused

Remove unused properties from ReactMount
Merge pull request #1642 from ryanseddon/trimCSSValues

Correctly trim strings for css properties
{Blog] Community Round-up #19
Change community roundup 19's React Bootstrap author to @stevoland