Merge pull request #324 from jeff1evesque/python_data_validator

#300: Remove duplicated uploads in 'data_validator.py'
#325: helper.py, adjust 'duplicate_list_index' docblock.
Merge pull request #326 from jeff1evesque/python_helper

#325: helper.py, adjust 'duplicate_list_index' docblock.
#300: data_validator.py correct typo suggested by @htoothrot
Merge pull request #328 from jeff1evesque/python_helper

#300: correct typo suggested by @htoothrot
#300: data_validator.py, change 'set_unique_hash' -> 'unique_hash'