correct issue of dangling µs in buckets

we are parsing at microsecond resolution, however the previous
floor methodology was only zeroing out seconds, not also
microseconds. This causes bucket alignment issues, and broke the
graphs page.

Change-Id: I688bb4bc9ef9fee2167dd2e94a25f060d4025afd

elastic_recheck/results.py

@@ -112,7 +112,9 @@ class FacetSet(dict):
             ts = datetime.datetime.strptime(data, "%Y-%m-%dT%H:%M:%S.%fZ")
             tsepoch = int(time.mktime(ts.timetuple()))
             # take the floor based on resolution
-            ts -= datetime.timedelta(seconds=(tsepoch % res))
+            ts -= datetime.timedelta(
+                seconds=(tsepoch % res),
+                microseconds=ts.microsecond)
             # ms since epoch
             epoch = datetime.datetime.utcfromtimestamp(0)
             pos = int(((ts - epoch).total_seconds()) * 1000)