comments added to AnswerChoiceCandAnsPMIScorer.java,
AnswerChoiceCandAnsSimilarityScorer.java, and
QuestionCandSentSimilarityMatcher.java
Merge branch 'master' into ernest

Conflicts:
	qa4mre-alzheimer-task/XMIs/12-test-alzheimer/QA4MRE-2012_BIOMEDICAL_GS.xml_1.xmi
	qa4mre-alzheimer-task/src/main/java/edu/cmu/lti/deiis/hw5/candidate_sentence/QuestionCandSentSimilarityMatcher.java
merged conflicts with the master
description of the type systems 7-13
Merge branch 'ernest'