Fixed another case of "too many SQL variables" error

When a tag already exists, the files of the old tag are re-assigned.
This causes another query that won't work on SQLite. Using
`chunked_bulk_create` fixes this.
Cleaned up old tests

- Removed broken selenium tests
- Removed simIMV.py
Made directory name readonly
Made product name readonly
Made package name readonly
Applied new readonly look to files
Names aren't changable in the backend now
Always reverse URLs instead of hardcoding them

- Use {% url 'url-name' %} in templates
- Use reverse('url-name') and redirect('url-name') in views
If a file has no hashes, show message.