Configurable loggers (file and console)

[nahuelhds]

You can now configure the logger handlers for the application.

# These are the default values
log: diffengine.log
logger:
  file: true
  console : false

The log property is the pre-existent one. I've added logger in order to be able to inactivate the file logger and/or activate the console logger. The latest is very handy when you wanna see what's happening in Heroku, for instance.

This can be safely merged as it doesn't conflict with the Twitter integration #71