Updated to v2 of Google's Speech API

* Made specifying a key mandatory
* Changed the way it looks for a FLAC converter
* Added option to show other guesses at what was said
* Added more bold stuff to README.rst
Added error checking

* And updated the readme
Add default key

* Added a default key so you can start using it straight away
Removed bad spacing in README.rst
Merge pull request #4 from bobsayshilol/master

Updated to v2 of Google's Speech API