Spiral Matrix II

	/**
	 * Given an integer n, generate a square matrix filled with elements
from 1
	 * to n2 in spiral order.
	 * 
	 * For example, Given n = 3,
	 * 
	 * You should return the following matrix:
	 * 
	 * 		[
			 [ 1, 2, 3 ],
			 [ 8, 9, 4 ],
			 [ 7, 6, 5 ]
			]
	 * 
	 * */