Selendroid-standalone: Fix to ScreenSize detection of emulators, and a feature - configurable maxSession and maxInstances

Hello!

1156fc5 
Fixed detection of screen resolution from skin name - 1st - made string comparison case insensitive, 2nd added a new skin.

779a077
This one is a bit more complicated. Not sure if you'll pull the commit.
Basic idea is to allow user to configure maxSession and maxInstances for config that is sent to grid on registering.

(somewhy github does not let met create a pull request for a single commit, so there are two commits in the request)

Thanks!

why isn't this `maxSessions`? That would be more consistent with `maxInstances`.