[ArmIncidentTracker] Check return value of soup_uri_new()

The previous code can't launch Hatohol server when an invalid URI
of an incident tracking server exists.
[ArmIncidentTracker] Free a SoupURI even if it's invalid
[Utils][DBTablesConfig] Validate URI on registering an incident tracking server
[Utils] Rename some validator function to unify naming rule

  validIP*Address ->
isValidIP*Address
Merge pull request #665 from project-hatohol/validate-incident-tracker-settings

Validate URI of an incident tracking server