Merge branch 'master' into develop
Issue #347 - Disallow known visited urls
Issue #439 - format duration as hh:mm:ss
Issue #439 - ensure backward compatibility

* If the duration is in seconds, interpret it that way.
Issue #439 - proper use of brackets for single statement
Issue #439 - fix duration format in resetSurveyInstance call
Merge branch 'master' into develop
Issue #439 - backward compatibility when duration is in numeric cell
Issue #439 - fix duration format in resetURLstring
Issue #441 - increase default placemark page size to 2000
Merge branch 'master' into develop
Merge branch 'release/1.6.8'