Check all date field for year before 1900

[sweemeng]

Currently it is breaking indexing's own checking because we have a year of value 1068

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/opt/apps/popit_env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/opt/apps/popit_env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 345, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/opt/apps/popit_env/local/lib/python2.7/site-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/opt/apps/popit_env/local/lib/python2.7/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/opt/apps/hluttaw/popit_ng/popit_search/management/commands/reindex.py", line 67, in handle
    popit_indexer(entity)
  File "/opt/apps/hluttaw/popit_ng/popit_search/utils/search.py", line 529, in popit_indexer
    bulk_indexer.index_data(to_index)
  File "/opt/apps/hluttaw/popit_ng/popit_search/utils/search.py", line 417, in index_data
    es_id=es_id, doc_type=entity_name, ops=ops, body=body
  File "/opt/apps/hluttaw/popit_ng/popit_search/utils/search.py", line 436, in create_bulk_entry
    body = sanitize_data(body)
  File "/opt/apps/hluttaw/popit_ng/popit_search/utils/search.py", line 543, in sanitize_data
    output[key] = new_date.strftime("%Y-%m-%dT%H%M%S")
ValueError: year=1068 is before 1900; the datetime strftime() methods require year >= 1900

[sweemeng]

dateutils parser is working correctly, but strftime refuse to convert back into text, this is important because elasticsearch only accept data as text