ensure s3 object key doesn't start with /

added expeceted s3 location build for partitions

dbRemoveTable now calls paws::s3()$delete_objects instead of paws::s3()$delete_object

replaced list_objects -> list_objects_v2 so that aws s3 objects can be iterated using aws tokens.

added expected data frame splitting methods

added timestamp parameter to write_parpuet