better ways to manage model specifications moving forward

[bstabler]

• We should think about a better way to manage model specifications moving forward
• As we build new submodels like transit pass ownership, we should figure out a good way to share / document / manage the model designs. Most work to date has been largely transferring existing designs/ideas
• Including documentation of data needs, where data came from for estimation, model development process, final results of what developed, etc.
• We're talking model documentation rather than user's guide (which is really more consistent with what we have today)
• In essence, how to build an ABM from the beginning