MAINT: Stop including progess field with minute performance result.

As currently implemented, progress doesn't currently make sense with
minutely results. Dropping the field from the results so should help
reduce some noise.

zipline/finance/performance.py

@@ -230,7 +230,6 @@ class PerformanceTracker(object):
         _dict = {
             'period_start': self.period_start,
             'period_end': self.period_end,
-            'progress': self.progress,
             'capital_base': self.capital_base,
             'cumulative_perf': self.cumulative_performance.to_dict(),
         }
@@ -238,7 +237,8 @@ class PerformanceTracker(object):
             _dict.update({'cumulative_risk_metrics':
                           self.cumulative_risk_metrics.to_dict(),
                           'daily_perf':
-                          self.todays_performance.to_dict()})
+                          self.todays_performance.to_dict(),
+                         'progress': self.progress})
         if self.emission_rate == 'minute':
             # Currently reusing 'todays_performance' for intraday trading
             # result, should be analogous, but has the potential for needing