Spiral Matrix

	/**
	 * Given a matrix of m x n elements (m rows, n columns), return all
elements
	 * of the matrix in spiral order.
	 * 
	 * For example, Given the following matrix:
	 * 
	 * [ 
	 * 	[ 1, 2, 3 ], 
	 *  [ 4, 5, 6 ], 
	 *  [ 7, 8, 9 ] 
	 * ] 
	 * 
	 * You should return
	 * 
	 * 		[1,2,3,6,9,8,7,4,5].
	 * 
	 * */