add two functions(moveHot2Cold, moveCold2Hot)
change Data's put function, add rm set
delte hot/cold cluster.java modify some imports in KVDaemon and InputHandler
add compress interface
add arguments in compress interface
compress interface implementation 1st
compress interface implementation 2st
modify pom.xml about guava
Merge branch 'master' into identify

Conflicts:
	src/main/java/cn/edu/sjtu/se/kvstore/common/ColdCluster.java
	src/main/java/cn/edu/sjtu/se/kvstore/common/HotCluster.java
	src/main/java/cn/edu/sjtu/se/kvstore/db/KVDaemon.java
finish integration!