Add the RMagick gem to the Gemfile
Add a preliminary script to generate thumbnails
Reindent make_thumbnail.rb using two-space tabs
Add UTF-8 encoding comment to make_thumbnail.rb
Trim comment lines to 79 characters
Add comments for thumbnail sizes
Remove unnecessary exit statement

Trollop will ensure that a value has been specified for the --file
option.
Add comments to make_thumbnail.rb
Don't generate thumbnails larger than the original
Compose the thumbnail filename with heredoc syntax