Make getChecked, getValue, handleChange private

Test Plan: grunt test, enter text in ballmer-peak example without any JS errors.
Merge pull request #275 from spicyj/input-private

Make getChecked, getValue, handleChange private
typo fix
Allow DOM Nodes in ImmutableObject

Currently, `ImmutableObject` will stack overflow while it tries to recurse and deep freeze all the properties of a DOM node.
Merge pull request #277 from stoyan/patch-1

typo fix
Added PyReact blog post.