ReportSpecifier.report_interval not supported  #123

report_service.py line 194 constructs ReportSpecifier object but does not set report_interval, in fact, a local variable named report_interval is assigned to report_back_duration in same line, and report_interval is assigned sampling_interval on line 182.

It would appear that report_interval provides a means for VTN to specify the reporting 'duration', otherwise set by VEN in oadrRegisterReport. oadrReport.duration, although the latter is a string (timedelta) and former is an interval (dtstart, duration, value). See oadr_ei_20b.xsd report_interval "This is the overall period of reporting."