Add my answer to Exercise 4.4.

Included is the following file:

	Exercise_4.4.scm

Thank you!
							Lawrence X. Amlord
							  Dec 17th, 2013
							  Xi'an, China
Update my answer to Exercise 4.1.

Fixed a typo:

	(rest-operands exp) --> (rest-operands exps)

in file:

	Exercise_4.1.scm

Thank you!
							Lawrence X. Amlord
							  Jan 15th, 2014
							  Fuzhou, China