add events for when a binding changes
Do not preventDefault on all keys.

This means `ctrl+R` and `f5`, etc don't work.

This is really annoying and out of scope.
Make kb-controls work from within an iframe.

Previously, listening to document.body for keyboard events
would not work when running a game within an iframe. So instead
kb-controls will attempt to listen to window.top.document.body,
or fall back to the original behaviour if there are cross-domain
issues.
Merge remote-tracking branch 'hughsk/iframe-fix'

https://github.com/chrisdickinson/kb-controls/pull/3
Merge remote-tracking branch 'raynos/patch-1'

https://github.com/chrisdickinson/kb-controls/pull/2
Add option to control enabling preventDefault()

Restores the original behavior of preventing defaults, by default,
so you can use Ctrl+R, F5, etc. in your web apps without triggering
the default browser behavior -- but adds a 'preventDefaults' option
to turn off default preventing if desired, for:

https://github.com/chrisdickinson/kb-controls/pull/2
Merge remote-tracking branch 'maxogden/changeevents'

https://github.com/chrisdickinson/kb-controls/pull/1
Split events emitter into up/down and use binding as event name

Allows for slightly more convenient event handling:

    ctl.down.on('foo', function() {
        ...
    });

instead of:

    ctl.events.on('change', function(binding, state) {
        if (binding === 'foo' && state >= 1) {
            ...
        }
    });
Listen for and prevent default on DOM 'contextmenu' event

Allows right-click to be used for other purposes. This default preventing
can be turned off with opts preventDefaults:false.
Update readme for options documentation