- add function to get reference from filename
- add function to move pdf from scan folder to process folder
- add function to delete pdfs from scan bucket for failed virus scans
* Added is_precompiled_letter method to letter/utils.py
* Added tests for letter/utils.py
* Added tests for the rest endpoint
* Moved the Precompiled name to a central location
* Added hidden field to the test method to create a template