Download missing files

[aloralove]

• downloads missing files
• looks to see what files are missing and downloads those specifically
• checks if all files are indeed in the event folder and creates metadata
• after the check of all files and metadata we mark it as complete
• added functions to create files in the in progress folder and move them over only when download is complete for that entire event folder
• the check missing looks through the in progress folder to find events to download

Future:

• [ ] might need to delete the complete events from the download progress folders??