Orphan Excel Importer

Part of Jira story: https://osraav.atlassian.net/browse/OSRA-70

Task: https://osraav.atlassian.net/browse/OSRA-163

- Using roo gem to parse Excel files
- Using rails_config gem to read yaml configuration settings for the importer
If I understand the intention of this test correctly, I would prefer the following for clarity:
```ruby
if @doc.last_row.nil? || (@doc.last_row < CONFIG.first_row)
```