moment assumes PST instead of UTC. Change moment to create object assuming UTC to stay consistent with BQ.

[mingjialiu]

moment(...) is local mode. Ambiguous input (without offset) is assumed to be local time. Unambiguous input (with offset) is adjusted to local time.
moment.utc(...) is utc mode. Ambiguous input is assumed to be UTC. Unambiguous input is adjusted to UTC.
[source for above]

This PR modifies bqutil.fn.cw_parse_timestamp to use moment.utc(...) to create timestamps assuming UTC to stay consistent with BQ.

eg:

SELECT
      parse_datetime('%Y%m%d %H%M%S', '20020211 123456') x,
      CAST(bqutil.fn.cw_parse_timestamp('20020211 123456789', 'YYYYMMDD HHmmssSSS') as DATETIME) z

outputs:

2002-02-11T12:34:56
2002-02-11T20:34:56.789000

They should be same with just difference in miliseconds.

[danieldeleo]

/gcbrun