Creates the greeting speaker app

We're hopefully going to synthesize greetings in lots of different
languages. How can this possibly go wrong?
Adds the content for the language picker

Really simple implementation - class with language name, bcp47 and
greeting. Standard UIPickerView stuff.
Adds the speech synthesis of the greetings

We make the SCGreetingLanguage objects generate utterances, with
appropriate voices. The view controller contains the synthesizer, and
utterances are queued when the button is pressed. This marks the sample
project as complete.
Adds write-up for AVSpeechSynthesizer
Adds the license copy to the header of the source files.
Merge branch 'days/04-avspeechsynthesizer'