modify the Pair*String*.java to avoid create String object in comparators, readField, write, compare functions are all updated, implementation iis done by referring to hadoop io Text class. instead of serielize String as UTF, use Text.write(String) to serialize it. so the serialization format is more reliable and consistent with hadoop serialization protocol
delete the commented old codes in previous modification
Fixed style.
Revamped documentation of reference implementations.
Merge branch 'imoldcat-master' into refactoring