Add answer to Exercise 1.8.

I've solved Exercise 1.8 in two different strategies. Note that
they are almost identical except for the definition of the 'good-
enough?' test and some other minor distinctions.

Included are the following 2 files:

	Exercise_1.8-Strategy_1.scm
	Exercise_1.8-Strategy_2.scm

Thank you!
						Lawrence R. Amlord
						   Apr 3, 2013
						   Xi'an, China