Create sample alexa skill that uses opent2t

[tjaffri]

sampleapps/alexa/ starts an alexa sample, specifically the speech assets.

It should be really simple to create a skill that implements "Alexa, turn on the lights" via opent2t. See the sampleapps/messenger-platform/ sample for motivation.

Also, note you can just use echosim.io to develop/test this sample. You don't really need a real echo.