Changed the output

This commit changes the output. The new output, when the user is
authenticated is:
{
	"user": {
		id: 3,
		username: 'foo',
		lastname: 'fooo',
		....
	},
	"courses" {
		"5":{
			"name":"My first course",
			"token":"caad14a34dc3582e1b0d9a83be6ae68b",
			"startdate": date
			....
		},
		"7":{
		  ....
		}
	}
}

This way the output contains both, user data and course data.
It is useful for mobile device because it gets the essential
data in one query.

Updated the Readme file.