Added getLastTraveredText to UiDevice
Remade the implementation of UiSelector. Now it is possible to use all methods of the UiSelector (except childSelector and fromParent). It is also possible to use multiple "selection-points" in a UiSelector (like: new UiSelector().text("something").className("android.widget.TextView"); ).
Updated a testcase to show off the multi "selection points" UiSelectors.