Better feature descriptions

Right now we have a very short description for each feature stored in `eis/features/`. Many of the descriptions are the same for each set of a class of features. To help people interpret these models, we should have a short, human readable name for every feature. For example, we have a class `Education` that correspond to a set of features for officer education level - one of which is called `is_high_school`. Ideally these would be as clear as possible: `officer_has_at_least_high_school_level_of_education`. In addition, it would be great if there were a string with a short description for the feature. In a frontend when you hover over a given "Risk Factor" (feature), this short description could be displayed, something like "A lower level of officer education has been shown in prior studies to be predictive of adverse incidents".