```ruby
#
# Ensure attachments are saved with URL-friendly names
Paperclip.interpolates :safe_filename do |attachment, style|
  filename(attachment, style).gsub(/#/, '-')
end
```

Allow xls files created via spreadsheet gem
user
```ruby
#
# Ensure attachments are saved with URL-friendly names
Paperclip.interpolates :safe_filename do |attachment, style|
  filename(attachment, style).gsub(/#/, '-')
end

# XLS files created by the spreadsheet gem have problems with their filetypes
# https://github.com/zdavatz/spreadsheet/issues/97
Paperclip.options[:content_type_mappings] = {
  xls: "CDF V2 Document, No summary info"
}
```
assistant