Voice recognition component

This is the first version of a component that encapsulates new Web Speech Api (https://dvcs.w3.org/hg/speech-api/raw-file/tip/speechapi.html) implementation that are in review on Firefox. 

This is its bug tree : https://bugzilla.mozilla.org/showdependencytree.cgi?id=1032964&hide_resolved=1

While the code does not land, we can use the following pre-built Nightly versions to test it:

Mac: https://www.dropbox.com/s/w0g4wptkcrvkjjb/firefox-32.0a1.en-US.mac64.dmg?dl=0