Added target and scheme for tvOS

Fixes #221

```
Test Suite 'SocketIO-tvOSTests.xctest' passed at 2015-10-22 17:21:34.436.
	 Executed 56 tests, with 0 failures (0 unexpected) in 0.817 (0.867) seconds
Test Suite 'All tests' passed at 2015-10-22 17:21:34.437.
	 Executed 56 tests, with 0 failures (0 unexpected) in 0.817 (0.868) seconds
````

Author: NachoSoto