Checking in the 3 job types plus the experimental 4th type.
There are 3 job types By Author, By Word , By Author By Word
AggregationByAuthor.java
By Author : each author is the key and value is count
			mapper emits authorname, 1
			combiner emits authorname, count
			reducer emits authorname, finalcount

AggregationByWord.java
By Word : each word (length more than 4 with
sanitization) is the keya and value is count
			mapper emits word, 1
			combiner emits word, count
			reducer emits word, finalcount

AggregationByAuthorWord.java
By Author By Word: each author is the key and value is word list
			mapper emits authorname, word
			combiner emits authorname, wordlist {word:count.....}
			reducer emits authorname, wordlist {word:count.....}

 AggregationAuthorWordEx.java
 Experimental class with custom key. goal is to use single parsing step
to get both authors and words. difficulty in getting the authorword (3rd
job type).Shows usage of custom keys.