* 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
* delete before check to avoid KeeperException$NoNodeException
* fix the message
* check processInstance state before delete tenant
* check processInstance state before delete worker group
* refactor
* merge api constants into common constatns
* update the resource perm
* update the dataSource perm
* fix CheckUtils.checkUserParams method
* update AlertGroupService, extends from BaseService, remove duplicate methods
* refactor
* modify method name
* add hasProjectAndPerm method
* using checkProject instead of getResultStatus
* delete checkAuth method, using hasProjectAndPerm instead.
* correct spelling
* add transactional for deleteWorkerGroupById
* add Transactional for deleteProcessInstanceById method
* change sqlSessionTemplate singleton
* change sqlSessionTemplate singleton and reformat code
* fix unsuitable error message
* update shutdownhook methods
* fix worker log bug
* fix api server debug mode bug
* upgrade zk version
* delete this line ,for zkClient.close() will do the whole thing
* fix master server shutdown error
* degrade zk version and add FourLetterWordMain class
* fix PathChildrenCache not close
* add Transactional for createSession method
* add more message for java-doc
* delete App, let spring manage connectionFactory
* add license
* add class Application for test support
* refactor masterServer and workerServer
* add args
* fix the spring transaction not work bug
* remove author
* delete @Bean annotation
* rename application.properties to application-dao.properties