JS: remove the separate threshold open/close callbacks, only provide the changed callback

Signed-off-by: Harvey Harrison <harvey.harrison@ausenco.com>
JS: add a helper method for making the ThresholdChanged callbacks

Signed-off-by: Harvey Harrison <harvey.harrison@ausenco.com>
JS: remove calcClosedTimeFromTime from Threshold

Signed-off-by: Harvey Harrison <harvey.harrison@ausenco.com>
JS: update version to 2014-20

Signed-off-by: Harvey Harrison <harvey.harrison@ausenco.com>