Add the carrierwave gem.
Use Carrierwave to store a question's image.
Use Carrierwave for an answer's photo.
Add ImageUploader#filename.
Fix the specs for Carrierwave for an answer.
Store the randomly generated portion of a photo's filename in the DB.

https://github.com/jnicklas/carrierwave/wiki/How-to%3A-Create-random-and
-unique-filenames-for-all-versioned-files
Don't send the photo_secure_token from backbone.
Generate a photo's filename based on the secure token.
Use S3 to store images
Add gems for carrierwave_backgrounder.
Configure carrierwave for S3.
Initialize carrierwave_backgrounder & delayed_job.
Question#image_in_base64 returns the cached image if it exists, otherwise the S3 image.
Save images to S3 with delayed_job.
Don't send Question#image_tmp from backbone.
Question#image_url returns the cached image if it exists, otherwise the S3 version.
Set the `cache_dir` for the ImageUploader.
Use `question.image_url` instead of `question.image.url`.
Question#image_url returns the URL to the image. Not the absolute path.
If the cached image is displayed for a question, show it at the right size.