DVPL-4301: Custom ReportingCommand crashes when it does not implement map operation

Fix:
+ Changed test for ReportingCommand.map override in ReportingCommand.ConfigurationSettings.fix_up
    Effect: We correctly identify when the ReportingCommand.map method is overridden and don't raise a KeyError when its not overridden.
+ Added check for ReportingCommand.map override in ReportingCommand.ConfigurationSettings.streaming_preop
    Effect: streaming_preop is only set if there's a map method override

Signed-off-by: David Noble <dnoble@splunk.com>