Add 20 dataset : each thread sends 1000 unique words pairs

src/DatafariTestThreads.java

src/dataset/query_datafari_th1.txt

src/dataset/query_datafari_th10.txt

src/dataset/query_datafari_th11.txt

src/dataset/query_datafari_th12.txt

src/dataset/query_datafari_th13.txt

src/dataset/query_datafari_th14.txt

src/dataset/query_datafari_th15.txt

src/dataset/query_datafari_th16.txt

src/dataset/query_datafari_th17.txt

src/dataset/query_datafari_th18.txt

src/dataset/query_datafari_th19.txt

src/dataset/query_datafari_th2.txt

src/dataset/query_datafari_th20.txt

src/dataset/query_datafari_th3.txt

src/dataset/query_datafari_th4.txt

src/dataset/query_datafari_th5.txt

src/dataset/query_datafari_th6.txt

src/dataset/query_datafari_th7.txt

src/dataset/query_datafari_th8.txt