[ALOY-1483] Support composite use of L(key) and strings in XML attribute values

<Alloy>
  <Label text="L('key') :" />
</Alloy>

    $.__views.__alloyId0 = Ti.UI.createLabel({
        text: 'L("time") :',
        id: "__alloyId0"
    });

    $.__views.__alloyId0 = Ti.UI.createLabel({
        text: L("time") + ' :',
        id: "__alloyId0"
    });