add in addEventListener shim from @wyuenho (0844b00c) to remove jQuery
dependency in History
add window.popstate checks for IE7 backwards compat
cleanup oldIE sniff code and iframe creation per @jdalton
remove first window argument from add/removeEventListener
check for onpopstate in window instead of window.onpopstate
Remove `_oldIE` variable.

* No need for `_oldIE` when we can just use `this.iframe`.
* Added `this._hasHashchange`.
Pass `useCapture` to `removeEventListener`.
Merge pull request #2 from braddunbar/history

Remove `_oldIE` variable.
Remove `isExplorer` RegEx.
Merge pull request #3 from braddunbar/history

Remove `isExplorer` RegEx.
Check `documentMode` and combine checks.
improve inline comments
Merge pull request #4 from braddunbar/history

Check `documentMode` and combine checks.
Remove `onpopstate` check.
Merge pull request #6 from braddunbar/history

Remove `onpopstate` check.
Add documentation to the iframe approach.
Merge pull request #9 from braddunbar/history

Resolve merge conflicts, add documentation.
Do not trigger router/history events if Router#execute returns false
Create iframe conditional on options and hashchange and pushstate support
Tweak a bit.