special override for _account_name (closes #16)

[davestimpert]

Basic, not-so-elegant solution to #16
Could be made more generic for complex columns, though this may be a one-of-a-kind situation so I didn't take time to over-engineer it.

[kevinschaich]

I think this should be ===

[kevinschaich]

This looks OK for now. If we run into this again, I think I'd prefer a "fallback list" for each column:

  const defaultTransactionColumns = [
    'date',
    'amount',
    'name',
    ['account_details.official_name', 'account_details.name'],
    'category.0',
    'category.1',
    'pending'
  ];

where in the code, we loop through and take the first value that is defined for that column.

[kevinschaich]

Closing in favor of #28, discussion to continue in #16