[ArmIncidentTracker] Fix a bug that ID in MonitoringServerInfo isn't initialized (issue #736)

Add a new spceial server ID "SERVER_ID_INCIDENT_TRACKE" for it.
[ArmBase] Fix a typo

setInitialTrrigerStatus ->
setInitialTriggerStatus
            ^^
[ArmBase] Add a new member function hasTrigger() (issue #736)

ArmBase has an issue that it stores self-monitoring triggers to DB
in spite of having no such triggers. To fix this issue, such a
function is needed.
[ArmBase] Don't store non-registered triggers to DB

Also events & hosts concerned with such triggers will be suppressed.
[testArmBase] Add tests for self-monitoring triggers

And move some generic functions from testDBTablesMonitoring to
Helper.{cc,h}.
Merge pull request #805 from project-hatohol/issue-736

Suppress needless self-monitoring triggers, events and hosts (issue #736)