pre-install tensorflow models

[RZachLamberty]

tensorflow has separated out the examples and tutorials files used throughout its documentation into a single separately-versioned github repository. it is a sizable enough that it doesn't make sense for individual users to have, but also important enough that multiple users will likely want it at some point

this would be a prime target for something that belongs in a /shared directory. this may be a part of a bigger project in which we rename the /data directory to be /shared and then start creating conceptually isolated subdirectories (e.g. /shared/data, /shared/documentation)

[RZachLamberty]

this would go in /shared/documentation in this scheme, fwiw