Python BigQuery source fails for timestamps < year 1900

This seems to be due to Python SDK using 'date.strftime' which has a known limitation.

[https://bugs.python.org/issue1777412](https://bugs.python.org/issue1777412)

This has been fixed for Python 3.3**** 

We might want to consider one of the workaround mentioned in the below post to fix BQ for Python 2.7.

[https://stackoverflow.com/questions/10263956/use-datetime-strftime-on-years-before-1900-require-year-1900](https://stackoverflow.com/questions/10263956/use-datetime-strftime-on-years-before-1900-require-year-1900)

This affects both Direct and Dataflow runners.

Imported from Jira [BEAM-4171](https://issues.apache.org/jira/browse/BEAM-4171). Original Jira may contain additional context.
Reported by: chamikara.