Added script and new target to help building Kiwi.framework using Kiwi-XCTest.

Followed process explained at: https://github.com/allending/Kiwi/wiki/Setting-Up-Kiwi-2.x-without-CocoaPods

Signed-off-by: Goffredo Marocchi <goffredo.marocchi@gamesys.co.uk>