[servers][testArmBase] Move initServerInfo() to Helpers so that other test can use it.
[server][HatoholArmPluginGate] Add a new stub class.
[server][HatoholArmPluginGate] Make the destructor protected to avoid a crash when its instance is created on a stack.
[server][HatoholArmPluginGate] Add interfaces for staring and stoping the thread.
[server][DBAgent::SelectArg] Add a new helper method: add().
[server][Helpers] Rename a test DB to be in the similar fashion with other setTestDB functions.
Merge pull request #180 from project-hatohol/issue-171

Issue 171