Implementing proposals for a model:

1. subclass RevisionMixin
2. Create a proxy model with RevisionManaggerMixin
3. decorate str with revision_str()
4. write a revision view
5. write a revision approval view
6. write a ModelAdmin

To Do:

• Dynamically add and remove intermediate models (ie. Reaction -> Stoichiometry -> Species)
• abstract views that use FormSets
• add rest of revision views
• Remove approve button if revision is already approved
• find a way to override str if model is a revision
• speed up form loading
• add django-autocomplete-light to admin

^ This is in reference to work done on #156