Speech Recognition extension prototyping

[ericrosenbaum]

Tasks for the next phase of prototyping a speech recognition extension:

• Use a “start listening” block to enable recognition for a single utterance
• Add UI sounds to indicate start and end of recognition
• Update the icon on all "when I hear" hats while listening
• Gather all inputs on "when I hear" hats on the start listening event
• Make the speech reporter monitor appear by default when the extension is loaded
• Switch over to using the cloud speech API