Update incidents by issue statuses.

Add "issuestatus" to the action configuration. Change the executable
file, checker class and some method names. Add method to update
incidents via PagerDuty REST API. Check the updated issues after
the log entries not to block existent functionality. Find back
incidents using using the remotelinks added before to the issues.
Update the incident statuses using the "status" on the action
configuration.

Add required notes to the action configuration paramters on
on the README file. Update the default action configuration to
make is work by default.