[TIMOB-17409] Both Ti.UI.View.rect and event coordinates should use the (same) documented unit

While making the [nl.fokkezb.color](https://github.com/fokkezb/nl.fokkezb.color) widget I noticed Ti.UI.View.rect and the x and y coordinate given in click (and other) events use different units. The documentation of [rect](http://docs.appcelerator.com/titanium/latest/#!/api/Titanium.UI.View-property-rect) clearly states it always uses the system unit (px on Android, dp on iOS) while the click docs (http://docs.appcelerator.com/titanium/latest/#!/api/Titanium.UI.View-event-click) don't specify the unit. When you execute the following app.js without and with ti.ui.defaultunit set to both dp and px on both platforms and click in the bottom right corner of the screen you'll see rect does *not* use the system unit but rather the defaultunit. The event coordinates *do* always use the system unit. The results can be found under the code snippet. The documentation should be fixed, but I'd also request for both to use the same units, be it system or default unit.

console.debug(Ti.App.Properties.getString('ti.ui.defaultunit'));
var win = Ti.UI.createWindow({backgroundColor:'white'});
win.addEventListener('postlayout', function(e) {
    console.debug('rect: ' + win.rect.width + ',' + win.rect.height);
});
win.addEventListener('click', function(e) {
    console.debug('click: ' + e.x + ',' + e.y);
});
win.open();

iOS

||ti.ui.defaultunit||rect||click|| |(none)|dp|dp| |px|px|dp| |dp|dp|dp|

Android

||ti.ui.defaultunit||rect||click|| |(none)|px|px| |px|px|px| |dp|dp|px|