* move updateTaskState into try/catch block in case of exception
* fix NPE
* using conf.getInt instead of getString
* for AbstractZKClient, remove the log, for it will print the same log message in createZNodePath.
for AlertDao, correct the spelling.
* duplicate
* refactor getTaskWorkerGroupId
* add friendly log
* update hearbeat thread num = 1
* fix the bug when worker execute task using queue. and remove checking Tenant user anymore in TaskScheduleThread
* 1. move verifyTaskInstanceIsNull after taskInstance
2. keep verifyTenantIsNull/verifyTaskInstanceIsNull clean and readable
* fix the message