handle changes to writeLog client function and clean up display name handling for tagging of event logs

changing format for event EMObservations and EMFootprint creation timestamps when these objects are converted to dicts

Adding custom pagination to superevents API to match events. It's bad, but will have to serve until we can redo the whole thing

updating event tag and event log tag resources to include more information than just a link to the detail page

adding superevent API urls - currently nesting them within the events API; should eventually be moved to a separate API app

generalizing and abstracting several models in the events app, as well as fixing many field parameters

Need to make sure values are actually numeric types before
just passing them to isnan(), since it can't handle them, apparently.

Adding some requirements to migrations to enforce proper ordering.