Add "build" action for the schemes
Update OS X test so they are buildable

- Set the correct OS X SDK Root
- Remove UIKit framework for OS X tests
Reintroduce the travis-ci badge
Prevent the -Wformat warning when using NSUInteger in the tests

    warning: values of type 'NSUInteger' should not be used as format arguments;
    add an explicit cast to 'unsigned long' instead [-Wformat]
Merge pull request #1609 from kylef/tests

Fix the tests for travis