[server][UnifiedDataStore] Improve the usability of getDataStore().

Forcing users to call unref() degrades the usability and is an
invitation to leak resources.

This patch resolves the above problems by using the stamrt pointer.
[server][ArmBase] Fix a grammatical mistake in the comment.
[server][ArmBase] Add a new method: getNonConstArmStatus().
[server][testArmBase] Reanme a test name due to the rename of the targert method.
[server][ArmStatus] Define stub methods: logSuccess() and logFailure().
[server][ArmBase] Remove 'NonConst' from a method name, because it is not popular and uncool.
[server][ArmStatus] Fix a bug that mistakenly uses readLock() in spite of an update.
[server][ArmStatus] Implement logSuccess().
[server][testArmStatus] Fix a grammatical mistake in the comment.
[server][ArmStatus] Implement logFailure().
[server][testArmBase] Enable OneProcHook to return false.
[server][ArmStatus] Use a more suitable name.
[server][ArmBase] Add a mechanism to log the result of  mainThreadOneProc().
[server][HatoholThreadBase] Use a atomic variable for MT-safe.
[server][testArmBase] Add tests for the failure of mainThreadOneProc().