Convert the timestamps in the postgres database to unix timestamp instead

[Niraj-Fonseka]

[ Current ] -

• Currently the datatype in the timestamp column is date time type. But this does not work well with gorm whenever we try to query for a set of records in a time range

[ Changes Needed ] -

• Change all the timestamps in to unix timestamp whenever we store in the database but convert them back to normal datetime / or not actually.