App instantiates with name in Unicode.

Previous declaration limited application names to ASCII character set. The OS X status bar supports Unicode strings.
Pass self instead of the type in setTarget_()
setTarget_ require a valid NSObject instance if we want the selector to work. Without a valid NSobject, the menuitem stay disabled.
Use unicode() instead of str() for possible unicode strings.
Merge unicode branch from https://github.com/hiroshi/rumps