Rename insertionPointParent to insertionParent

This is to match WebKit.

Fixes #83
Update mocha version to 1.9 or greater
Update README.md
Implement event constructors for Safari and IE

This implements event constructors for

Event
CustomEvent
UIEvent
MouseEvent
FocusEvent

More can easily be added as needed.

Fixes #58
Wrap getComputedStyle

Fixes #64
Override document.{body,head}.{appendChild,insertBefore,replaceChild,removeChild}

To be able to support this the Node methods can no longer call
`this.impl.appendChild` and instead we call `originalAppendChild.call`.