Added `componentWillUpdate` lifecycle wrapper...

Adds the `on-will-update` and `on-will-render` lifecycle wrapper fn's.
These can be used to prepare the page for an update, e.g. by adding or
removing a class to trigger an animation.
Merge branch 'master' of github.com:levand/quiescent
Fixed missing paren
Merge pull request #14 from OtherPeoplesPixels/master

Add `componentWillUpdate` lifecycle wrapper