Returns whether Unpoly supports the current browser.
If this returns
false Unpoly will prevent itself from booting
and ignores all registered event handlers and compilers.
This leaves you with a classic server-side application.
many errors on load.
This function also returns
true if Unpoly only support some features, but can degrade
gracefully for other features. E.g. Internet Explorer 9 is almost fully supported, but due to
its lack of
Unpoly falls back to a full page load when asked to manipulate history.