add two more functions to NSWorkspace

I'm exposing two functions on NSWorkspace. My goal is to get a NSRunningApplication instance of the launching application. So that I can get its PID along with some other information. launchAppWithBundleIdentifier doesn't give me that.

Ran `rake` command, so far it passes all core extra and highlighter tests.
During testing,  I found the AXElementTester project build failed, the Info.plist file is missing in repo. so I added it. But I'm not sure if the version is correct.

Also `test_post` method failed on my 10.9.2 system, because it uses deprecated function. so I skip it on Sea Lion. (should I say Mavericks?)

Thanks for reviewing!
-Jonny