[ALOY-625] app.tss not being applied to views that don't have controller-specific styles

problem

app.tss files are not being applied to views/controllers that don't have controller-specific styles. For example:

index.xml

<Alloy>
	<Window class="container">
		<Label id="label">Hello, World</Label>
	</Window>
</Alloy>

app.tss

".container": {
	backgroundColor:"#888"
}

"Label": {
	width: Ti.UI.SIZE,
	height: Ti.UI.SIZE,
	color: "#f00"
} 

The above will not apply the app.tss styles to the appropriate components in the index.xml file.

workaround

Creating a blank TSS file "index.tss" will apply the global style.