Update core/src/main/java/com/orientechnologies/orient/core/id/OClusterPosition.java

Add equals function
Update core/src/main/java/com/orientechnologies/orient/core/storage/OPhysicalPosition.java

replace == to equals function
fix conflict
Update server/src/main/java/com/orientechnologies/orient/server/distributed/OStorageSynchronizer.java

Reduce risk for infinite loop
Update server/src/main/java/com/orientechnologies/orient/server/distributed/ODistributedAbstractPlugin.java

Reduce risk for infinite loop
add OPhysicalPosition.java which accidently removed
Merge pull request #1301 from henryzhao81/master

Reduce risk for infinite loop