Fix python bindings ESmry, start date

[tskille]

This PR fixes handling of daylight-saving time when importing start date from a summary file (and ESMRY) using python bindings.

Consider the following example. Start date is set in the data deck.

-- daylight saving from 2020-03-29 02:00 -> 03:00
START
 29 'MAR' 2020 05:04:41 /

When running this deck with OPM Flow, the following is saved to the SMSPEC file

'STARTDAT'           6 'INTE'
          29           3        2020           5           4    41000000

So far, all good.

However, when using the following python script to import start date from the summary file

import sys

from opm.io.ecl import ESmry

if __name__ == "__main__":

    smry = ESmry(sys.argv[1])

    print ("\n start date > {} \n".format(smry.start_date))

results are as following

start date > 2020-03-29 06:04:41

This is not as expected. As could be seen, this is one hour shifted relative to the input and to what is stored in the SMSPEC file.