Create new method for storing / distributing large files for IMAGE server (models, etc)

[jeffbl]

Currently, we store all our large files on sharepoint, then when they are updated, manually transfer them to unicorn, and rsync them to pegasus. This is error prone, and obscure to people on the project. Some files are also simply uploaded directly to unicorn, and are therefore not backed up until we notice this happened. Work item is to figure out a better process that is less error prone.

Note that this is discussed briefly in the FAQ on this wiki page, including some of the other tools we originally considered.