First version of kurento-tutorial-node for node

It contains the final version of kurento-hello-world and preliminary versions of kurento-magic-mirror and kurento-one2many

Change-Id: I429b473d4314ba91dc5ef78ce7d6507c0a370603

Improved kurento-magic-mirror tutorial

Change-Id: I6557476657ad1b515190efb005d4102e7fa3c0e1