[server][UnifiedDataStore] Add makers to help us remove VirtualDataStore.
[server][DataStoreFactory] Add a new class: DataStoreFactory.
[server][DataStoreFactory] Add test parameters for test_createWithInvalidTypes().
[server][testDataStoreFactory] Add test for create() with a normal paramter.
[server][testDataStoreFactory] Fix a potential problem that might leak a memory.
[server][DataStoreFactory] Change a severity level.
[server][testDataStoreFactory] Add a paramter to create ArmZabbixAPI.
[server][testDataStoreFactory] Add a paramter to create ArmNagiosNDOUtils.
[server][DBClientConfig] Define a new type: MonitoringServerInfoListConstIterator.
[server][UnifiedDataStore] Make some members private to enhance encapsulation of PrivateContext.
[server][UnifiedDataStore] Break away from VirtualDataStore.
[server][VirtualDataStoreFake] Remove VirtualDataStoreFake that is no longer used.
[server][VirtualDataStoreNagios] Remove VirtualDataStoreNagios that is no longer used.
[server][VirtualDataStoreZabbix] Remove VirtualDataStore that is no longer used.
[server][VirtualDataStore][VirtualDataStoreFactory] Remove classes that are no longer used.
[server][SQLProcessorZabbix] Delete SQLProcessorZabbix that doesn't work well and is not needed now.
Merge pull request #191 from project-hatohol/issue-171

Issue 171