Automatically selects the latest version of the app to test if it is not specified by users.

Add code to SelendroidCapabilities.java to select the latest
version of the app to test if the app version is not provided by
the users.

Add a new unit test class SelendroidCapabilitiesSplitNamesTest.java

Signed-off-by: Binh Vu <bvu@paypal.com>