Use ArrayBufferView for sending data when it's available

Fixes #85 and #100

Chrome 22 [deprecated using ArrayBuffer in XHR2.send](http://updates.html5rocks.com/2012/07/Arrived-xhr-send-ArrayBufferViews), introducing the more preferred `ArrayBufferView` object.  Apparently this was a change made in reaction to the [spec itself](http://dvcs.w3.org/hg/xhr/raw-file/tip/Overview.html#dom-xmlhttprequest-send) changing, so it's reasonable to assume than any browser that does not implement `ArrayBufferView` supports the old style, while those that do implement it support the new style.