[s3] Merge remote-tracking branch 'upstream/master'

.travis.yml

README.md

...pike/src/main/java/com/yahoo/ycsb/db/AerospikeClient.java

bin/ycsb

...a/src/main/java/com/yahoo/ycsb/db/CassandraCQLClient.java

...om/yahoo/ycsb/generator/AcknowledgedCounterGenerator.java

...m/yahoo/ycsb/measurements/OneMeasurementHdrHistogram.java

...ahoo/ycsb/generator/AcknowledgedCounterGeneratorTest.java

doc/javadoc/allclasses-frame.html

doc/javadoc/allclasses-noframe.html

doc/javadoc/com/yahoo/ycsb/BasicDB.html

doc/javadoc/com/yahoo/ycsb/Client.html

doc/javadoc/com/yahoo/ycsb/CounterGenerator.html

doc/javadoc/com/yahoo/ycsb/DB.html

doc/javadoc/com/yahoo/ycsb/DBException.html

doc/javadoc/com/yahoo/ycsb/DBFactory.html

doc/javadoc/com/yahoo/ycsb/DBWrapper.html

doc/javadoc/com/yahoo/ycsb/DiscreteGenerator.html

doc/javadoc/com/yahoo/ycsb/FindGoodAB.html

doc/javadoc/com/yahoo/ycsb/FindGoodScrambleVector.html