Split app name and version in Capabilities

To enhance capability matching and select the latest version of the app to test if the
app version is not provided by the users.

Signed-off-by: Binh Vu <bvu@paypal.com>
I don't think calling this `SELENIUM_NATIVE_APP_VERSION` make sense. As coded, only the selendroid integration will make use of it. 

@azaytsev Could our ios-driver integration make use of this config param?

Also FYI, I realize you followed the approach used by `SELENIUM_NATIVE_APP_NAME` here but it's case I'm not sure it makes sense to have as a Config variable. My reason for saying this -- I just don't realistically see a world where a single Native app Test will work across multiple apps without significant `if` .. `else` constructs in the Test. Certainly, the PayPal native app Test wont work for the eBay native app and vice-versa.. Thoughts on this?