correct my solution to exercises in Recitation 10.

The solution is revised in terms of that one provided by
6.005 course staff, located in package "staff".

Modified is the following file:

	Recitations/R10-Concurrency/src/lawrence/Grep.java

Thank you!
							Lawrence X. Amlord
							  Nov. 11th, 2014
							   Xi'an, China